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<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:dc="http://purl.org/dc/terms/" xmlns:doi="http://dx.doi.org/" lang="en" xml:lang="en" itemscope itemtype="http://schema.org/Article" class="no-js"> <head prefix="og: http://ogp.me/ns#"> <link rel="stylesheet" href="/resource/css/screen.css?79f248ebefa43b7800a14562e5049ab4"/>   <link rel="stylesheet" type="text/css" href="https://fonts.googleapis.com/css?family=Open+Sans:400,400i,600"> <link media="print" rel="stylesheet" type="text/css" href="/resource/css/print.css"/> <script type="text/javascript"> var siteUrlPrefix = "/plosone/"; </script> <script src="/resource/js/vendor/modernizr-v2.7.1.js" type="text/javascript"></script> <script src="/resource/js/vendor/detectizr.min.js" type="text/javascript"></script> <link rel="shortcut icon" href="/resource/img/favicon.ico" type="image/x-icon"/> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <link rel="canonical" href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0249090" /> <meta name="description" content="Background Asymptomatic SARS-CoV-2 infections are responsible for potentially significant transmission of COVID-19. Worldwide, a number of studies were conducted to estimate the magnitude of asymptomatic COVID-19 cases. However, there is a need for more robust and well-designed studies to have a relevant public health intervention. Synthesis of the available studies significantly strengthens the quality of evidences for public health practice. Thus, this systematic review and meta-analysis aimed to determine the overall magnitude of asymptomatic COVID-19 cases throughout the course of infection using available evidences. Methods We followed the PRISMA checklist to present this study. Two experienced review authors (MA and DBK) were systematically searched international electronic databases for studies. We performed meta-analysis using R statistical software. The overall weighted proportion of asymptomatic COVID-19 cases throughout the course infection was computed. The pooled estimates with 95% confidence intervals were presented using forest plot. Egger’s tests were used to assess publication bias, and primary estimates were pooled using a random effects model. Furthermore, a sensitivity analysis was conducted to assure the robustness of the result. Results A total of 28 studies that satisfied the eligibility criteria were included in this systematic review and meta-analysis. Consequently, in the meta-analysis, a total of 6,071 COVID-19 cases were included. The proportion of asymptomatic infections among the included studies ranged from 1.4% to 78.3%. The findings of this meta-analysis showed that the weighted pooled proportion of asymptomatic COVID-19 cases throughout the course of infection was 25% (95%CI: 16–38). The leave-one out result also revealed that the weighted pooled average of asymptomatic SARS-CoV-2 infection was between 28% and 31.4%. Conclusions In conclusion, one-fourth of SARS-CoV-2 infections are remained asymptomatic throughout the course infection. Scale-up of testing, which targeting high risk populations is recommended to tackle the pandemic." /> <meta name="citation_abstract" content="Background Asymptomatic SARS-CoV-2 infections are responsible for potentially significant transmission of COVID-19. Worldwide, a number of studies were conducted to estimate the magnitude of asymptomatic COVID-19 cases. However, there is a need for more robust and well-designed studies to have a relevant public health intervention. Synthesis of the available studies significantly strengthens the quality of evidences for public health practice. Thus, this systematic review and meta-analysis aimed to determine the overall magnitude of asymptomatic COVID-19 cases throughout the course of infection using available evidences. Methods We followed the PRISMA checklist to present this study. Two experienced review authors (MA and DBK) were systematically searched international electronic databases for studies. We performed meta-analysis using R statistical software. The overall weighted proportion of asymptomatic COVID-19 cases throughout the course infection was computed. The pooled estimates with 95% confidence intervals were presented using forest plot. Egger’s tests were used to assess publication bias, and primary estimates were pooled using a random effects model. Furthermore, a sensitivity analysis was conducted to assure the robustness of the result. Results A total of 28 studies that satisfied the eligibility criteria were included in this systematic review and meta-analysis. Consequently, in the meta-analysis, a total of 6,071 COVID-19 cases were included. The proportion of asymptomatic infections among the included studies ranged from 1.4% to 78.3%. The findings of this meta-analysis showed that the weighted pooled proportion of asymptomatic COVID-19 cases throughout the course of infection was 25% (95%CI: 16–38). The leave-one out result also revealed that the weighted pooled average of asymptomatic SARS-CoV-2 infection was between 28% and 31.4%. Conclusions In conclusion, one-fourth of SARS-CoV-2 infections are remained asymptomatic throughout the course infection. Scale-up of testing, which targeting high risk populations is recommended to tackle the pandemic."> <meta name="keywords" content="COVID 19,Respiratory infections,SARS CoV 2,Metaanalysis,Systematic reviews,Virus testing,Pandemics,Database searching" /> <meta name="citation_doi" content="10.1371/journal.pone.0249090"/> <meta name="citation_author" content="Muluneh Alene"/> <meta name="citation_author_institution" content="Department of Public Health, Debre Markos University, Debre Markos, Ethiopia"/> <meta name="citation_author" content="Leltework Yismaw"/> <meta name="citation_author_institution" content="Department of Public Health, Debre Markos University, Debre Markos, Ethiopia"/> <meta name="citation_author" content="Moges Agazhe Assemie"/> <meta name="citation_author_institution" content="Department of Public Health, Debre Markos University, Debre Markos, Ethiopia"/> <meta name="citation_author" content="Daniel Bekele Ketema"/> <meta name="citation_author_institution" content="Department of Public Health, Debre Markos University, Debre Markos, Ethiopia"/> <meta name="citation_author" content="Belayneh Mengist"/> <meta name="citation_author_institution" content="Department of Public Health, Debre Markos University, Debre Markos, Ethiopia"/> <meta name="citation_author" content="Bekalu Kassie"/> <meta name="citation_author_institution" content="Department of Midwifery, Debre Markos University, Debre Markos, Ethiopia"/> <meta name="citation_author" content="Tilahun Yemanu Birhan"/> <meta name="citation_author_institution" content="Department of Epidemiology and Biostatistics, University of Gondar, Gondar, Ethiopia"/> <meta name="citation_title" content="Magnitude of asymptomatic COVID-19 cases throughout the course of infection: A systematic review and meta-analysis"/> <meta itemprop="name" content="Magnitude of asymptomatic COVID-19 cases throughout the course of infection: A systematic review and meta-analysis"/> <meta name="citation_journal_title" content="PLOS ONE"/> <meta name="citation_journal_abbrev" content="PLOS ONE"/> <meta name="citation_date" content="Mar 23, 2021"/> <meta name="citation_firstpage" content="e0249090"/> <meta name="citation_issue" content="3"/> <meta name="citation_volume" content="16"/> <meta name="citation_issn" content="1932-6203"/> <meta name="citation_publisher" content="Public Library of Science"/> <meta name="citation_pdf_url" content="https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0249090&type=printable"> <meta name="citation_article_type" content="Research Article"> <meta name="dc.identifier" content="10.1371/journal.pone.0249090" /> <meta name="twitter:card" content="summary" /> <meta name="twitter:site" content="plosone"/> <meta name="twitter:title" content="Magnitude of asymptomatic COVID-19 cases throughout the course of infection: A systematic review and meta-analysis" /> <meta property="twitter:description" content="Background Asymptomatic SARS-CoV-2 infections are responsible for potentially significant transmission of COVID-19. Worldwide, a number of studies were conducted to estimate the magnitude of asymptomatic COVID-19 cases. However, there is a need for more robust and well-designed studies to have a relevant public health intervention. Synthesis of the available studies significantly strengthens the quality of evidences for public health practice. Thus, this systematic review and meta-analysis aimed to determine the overall magnitude of asymptomatic COVID-19 cases throughout the course of infection using available evidences. Methods We followed the PRISMA checklist to present this study. Two experienced review authors (MA and DBK) were systematically searched international electronic databases for studies. We performed meta-analysis using R statistical software. The overall weighted proportion of asymptomatic COVID-19 cases throughout the course infection was computed. The pooled estimates with 95% confidence intervals were presented using forest plot. Egger’s tests were used to assess publication bias, and primary estimates were pooled using a random effects model. Furthermore, a sensitivity analysis was conducted to assure the robustness of the result. Results A total of 28 studies that satisfied the eligibility criteria were included in this systematic review and meta-analysis. Consequently, in the meta-analysis, a total of 6,071 COVID-19 cases were included. The proportion of asymptomatic infections among the included studies ranged from 1.4% to 78.3%. The findings of this meta-analysis showed that the weighted pooled proportion of asymptomatic COVID-19 cases throughout the course of infection was 25% (95%CI: 16–38). The leave-one out result also revealed that the weighted pooled average of asymptomatic SARS-CoV-2 infection was between 28% and 31.4%. Conclusions In conclusion, one-fourth of SARS-CoV-2 infections are remained asymptomatic throughout the course infection. Scale-up of testing, which targeting high risk populations is recommended to tackle the pandemic." /> <meta property="twitter:image" content="https://journals.plos.org/plosone/article/figure/image?id=10.1371/journal.pone.0249090.g003&size=inline" /> <meta property="og:type" content="article" /> <meta property="og:url" content="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0249090"/> <meta property="og:title" content="Magnitude of asymptomatic COVID-19 cases throughout the course of infection: A systematic review and meta-analysis"/> <meta property="og:description" content="Background Asymptomatic SARS-CoV-2 infections are responsible for potentially significant transmission of COVID-19. Worldwide, a number of studies were conducted to estimate the magnitude of asymptomatic COVID-19 cases. However, there is a need for more robust and well-designed studies to have a relevant public health intervention. Synthesis of the available studies significantly strengthens the quality of evidences for public health practice. Thus, this systematic review and meta-analysis aimed to determine the overall magnitude of asymptomatic COVID-19 cases throughout the course of infection using available evidences. Methods We followed the PRISMA checklist to present this study. Two experienced review authors (MA and DBK) were systematically searched international electronic databases for studies. We performed meta-analysis using R statistical software. The overall weighted proportion of asymptomatic COVID-19 cases throughout the course infection was computed. The pooled estimates with 95% confidence intervals were presented using forest plot. Egger’s tests were used to assess publication bias, and primary estimates were pooled using a random effects model. Furthermore, a sensitivity analysis was conducted to assure the robustness of the result. Results A total of 28 studies that satisfied the eligibility criteria were included in this systematic review and meta-analysis. Consequently, in the meta-analysis, a total of 6,071 COVID-19 cases were included. The proportion of asymptomatic infections among the included studies ranged from 1.4% to 78.3%. The findings of this meta-analysis showed that the weighted pooled proportion of asymptomatic COVID-19 cases throughout the course of infection was 25% (95%CI: 16–38). The leave-one out result also revealed that the weighted pooled average of asymptomatic SARS-CoV-2 infection was between 28% and 31.4%. Conclusions In conclusion, one-fourth of SARS-CoV-2 infections are remained asymptomatic throughout the course infection. Scale-up of testing, which targeting high risk populations is recommended to tackle the pandemic."/> <meta property="og:image" content="https://journals.plos.org/plosone/article/figure/image?id=10.1371/journal.pone.0249090.g003&size=inline"/> <meta name="citation_reference" content="WHO. media briefing on COVID-19–11 March 2020. Accessed from https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19—11-march-2020 ."/> <meta name="citation_reference" content="citation_title=The Global Economic Outlook During the COVID-19 Pandemic: A Changed World;citation_journal_title=The Global Economic Outlook During the COVID-19 Pandemic: A Changed World;citation_publication_date=2020;"/> <meta name="citation_reference" content="JHONS HOPKINS coronavirus resource center.COVID-19. Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU)."/> <meta name="citation_reference" content="citation_title=Three months of COVID‐19: A systematic review and meta‐analysis;citation_author=D Rafiq;citation_author=A Batool;citation_author=MA Bazaz;citation_journal_title=Reviews in Medical Virology;citation_volume=18;citation_number=18;citation_first_page=e2113;citation_publication_date=2020;"/> <meta name="citation_reference" content="citation_title=The Prevalence of Symptoms in 24,410 Adults Infected by the Novel Coronavirus (SARS-CoV-2; COVID-19): A Systematic Review and Meta-Analysis of 148 Studies from 9 Countries;citation_author=MC Grant;citation_author=L Geoghegan;citation_author=M Arbyn;citation_author=Z Mohammed;citation_author=L McGuinness;citation_author=EL Clarke;citation_journal_title=Avail;"/> <meta name="citation_reference" content="citation_title=Asymptomatic patients as a source of COVID-19 infections: A systematic 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class="article-meta"> <div class="classifications"> <p class="license-short" id="licenseShort">Open Access</p> <p class="peer-reviewed" id="peerReviewed">Peer-reviewed</p> <div class="article-type" > <p class="type-article" id="artType">Research Article</p> </div> </div> </div> <div class="article-title-etc"> <div class="title-authors"> <h1 id="artTitle"><?xml version="1.0" encoding="UTF-8"?>Magnitude of asymptomatic COVID-19 cases throughout the course of infection: A systematic review and meta-analysis</h1> <ul class="author-list clearfix" data-js-tooltip="tooltip_container" id="author-list"> <li data-js-tooltip="tooltip_trigger" > <a data-author-id="0" class="author-name" > Muluneh Alene <span class="email"> </span>,</a> <div id="author-meta-0" class="author-info" data-js-tooltip="tooltip_target"> <p class="roles" id="authRoles"> <span class="type">Roles</span> Conceptualization, Data curation, Formal analysis, Methodology, Software, Validation, Writing – original draft, Writing – review & editing </p> <p id="authCorresponding-0"> <span class="email">* E-mail:</span> <a href="mailto:mulunehadis@gmail.com">mulunehadis@gmail.com</a></p> <p id="authAffiliations-0"><span class="type">Affiliation</span> Department of Public Health, Debre Markos University, Debre Markos, Ethiopia </p> <div> <p class="orcid" id="authOrcid-0"> <span> <a id="connect-orcid-link" href="https://orcid.org/0000-0002-1485-9014" target="_blank" title="ORCID Registry"> <img id="orcid-id-logo" src="/resource/img/orcid_16x16.png" width="16" height="16" alt="ORCID logo"/> https://orcid.org/0000-0002-1485-9014 </a> </span> </p> </div> <a data-js-tooltip="tooltip_close" class="close" id="tooltipClose0"> ⨯ </a> </div> </li> <li data-js-tooltip="tooltip_trigger" > <a data-author-id="1" class="author-name" > Leltework Yismaw,</a> <div id="author-meta-1" class="author-info" data-js-tooltip="tooltip_target"> <p class="roles" id="authRoles"> <span class="type">Roles</span> Data curation, Formal analysis, Investigation, Methodology, Validation, Writing – review & editing </p> <p id="authAffiliations-1"><span class="type">Affiliation</span> Department of Public Health, Debre Markos University, Debre Markos, Ethiopia </p> <a data-js-tooltip="tooltip_close" class="close" id="tooltipClose1"> ⨯ </a> </div> </li> <li data-js-tooltip="tooltip_trigger" > <a data-author-id="2" class="author-name" > Moges Agazhe Assemie,</a> <div id="author-meta-2" class="author-info" data-js-tooltip="tooltip_target"> <p class="roles" id="authRoles"> <span class="type">Roles</span> Data curation, Formal analysis, Investigation, Methodology, Supervision, Writing – original draft, Writing – review & editing </p> <p id="authAffiliations-2"><span class="type">Affiliation</span> Department of Public Health, Debre Markos University, Debre Markos, Ethiopia </p> <div> <p class="orcid" id="authOrcid-2"> <span> <a id="connect-orcid-link" href="https://orcid.org/0000-0003-0380-834X" target="_blank" title="ORCID Registry"> <img id="orcid-id-logo" src="/resource/img/orcid_16x16.png" width="16" height="16" alt="ORCID logo"/> https://orcid.org/0000-0003-0380-834X </a> </span> </p> </div> <a data-js-tooltip="tooltip_close" class="close" id="tooltipClose2"> ⨯ </a> </div> </li> <li data-js-tooltip="tooltip_trigger" > <a data-author-id="3" class="author-name" > Daniel Bekele Ketema,</a> <div id="author-meta-3" class="author-info" data-js-tooltip="tooltip_target"> <p class="roles" id="authRoles"> <span class="type">Roles</span> Conceptualization, Formal analysis, Investigation, Methodology, Supervision, Validation, Writing – original draft </p> <p id="authAffiliations-3"><span class="type">Affiliation</span> Department of Public Health, Debre Markos University, Debre Markos, Ethiopia </p> <a data-js-tooltip="tooltip_close" class="close" id="tooltipClose3"> ⨯ </a> </div> </li> <li data-js-tooltip="tooltip_trigger" > <a data-author-id="4" class="author-name" > Belayneh Mengist,</a> <div id="author-meta-4" class="author-info" data-js-tooltip="tooltip_target"> <p class="roles" id="authRoles"> <span class="type">Roles</span> Conceptualization, Data curation, Formal analysis, Methodology, Validation, Writing – original draft, Writing – review & editing </p> <p id="authAffiliations-4"><span class="type">Affiliation</span> Department of Public Health, Debre Markos University, Debre Markos, Ethiopia </p> <div> <p class="orcid" id="authOrcid-4"> <span> <a id="connect-orcid-link" href="https://orcid.org/0000-0002-0363-8777" target="_blank" title="ORCID Registry"> <img id="orcid-id-logo" src="/resource/img/orcid_16x16.png" width="16" height="16" alt="ORCID logo"/> https://orcid.org/0000-0002-0363-8777 </a> </span> </p> </div> <a data-js-tooltip="tooltip_close" class="close" id="tooltipClose4"> ⨯ </a> </div> </li> <li data-js-tooltip="tooltip_trigger" > <a data-author-id="5" class="author-name" > Bekalu Kassie,</a> <div id="author-meta-5" class="author-info" data-js-tooltip="tooltip_target"> <p class="roles" id="authRoles"> <span class="type">Roles</span> Data curation, Formal analysis, Investigation, Supervision, Validation, Writing – review & editing </p> <p id="authAffiliations-5"><span class="type">Affiliation</span> Department of Midwifery, Debre Markos University, Debre Markos, Ethiopia </p> <a data-js-tooltip="tooltip_close" class="close" id="tooltipClose5"> ⨯ </a> </div> </li> <li data-js-tooltip="tooltip_trigger" > <a data-author-id="6" class="author-name" > Tilahun Yemanu Birhan</a> <div id="author-meta-6" class="author-info" data-js-tooltip="tooltip_target"> <p class="roles" id="authRoles"> <span class="type">Roles</span> Data curation, Formal analysis, Investigation, Methodology, Supervision, Validation, Visualization, Writing – review & editing </p> <p id="authAffiliations-6"><span class="type">Affiliation</span> Department of Epidemiology and Biostatistics, University of Gondar, Gondar, Ethiopia </p> <a data-js-tooltip="tooltip_close" class="close" id="tooltipClose6"> ⨯ </a> </div> </li> </ul> <script src="/resource/js/components/tooltip.js" type="text/javascript"></script> </div> <div id="floatTitleTop" data-js-floater="title_author" class="float-title" role="presentation"> <div class="set-grid"> <div class="float-title-inner"> <h1><?xml version="1.0" encoding="UTF-8"?>Magnitude of asymptomatic COVID-19 cases throughout the course of infection: A systematic review and meta-analysis</h1> <ul id="floatAuthorList" data-js-floater="floated_authors"> <li data-float-index="1">Muluneh Alene,  </li> <li data-float-index="2">Leltework Yismaw,  </li> <li data-float-index="3">Moges Agazhe Assemie,  </li> <li data-float-index="4">Daniel Bekele Ketema,  </li> <li data-float-index="5">Belayneh Mengist,  </li> <li data-float-index="6">Bekalu Kassie,  </li> <li data-float-index="7">Tilahun Yemanu Birhan </li> </ul> </div> <div class="logo-close" id="titleTopCloser"> <img src="/resource/img/logo-plos.png" style="height: 2em" alt="PLOS" /> <div 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class="carousel-page-buttons"> </div> </div> </div> <script src="/resource/js/vendor/jquery.touchswipe.js" type="text/javascript"></script> <script src="/resource/js/components/figure_carousel.js" type="text/javascript"></script> <script src="/resource/js/vendor/jquery.dotdotdot.js" type="text/javascript"></script> <div class="article-text" id="artText"> <div xmlns:plos="http://plos.org" class="abstract toc-section abstract-type-"><a id="abstract0" name="abstract0" data-toc="abstract0" class="link-target" title="Abstract"></a><h2>Abstract</h2><div class="abstract-content"> <div id="section1" class="section toc-section"><a id="sec001" name="sec001" class="link-target" title="Background"></a> <h3>Background</h3> <a id="article1.front1.article-meta1.abstract1.sec1.p1" name="article1.front1.article-meta1.abstract1.sec1.p1" class="link-target"></a><p>Asymptomatic SARS-CoV-2 infections are responsible for potentially significant transmission of COVID-19. Worldwide, a number of studies were conducted to estimate the magnitude of asymptomatic COVID-19 cases. However, there is a need for more robust and well-designed studies to have a relevant public health intervention. Synthesis of the available studies significantly strengthens the quality of evidences for public health practice. Thus, this systematic review and meta-analysis aimed to determine the overall magnitude of asymptomatic COVID-19 cases throughout the course of infection using available evidences.</p> </div> <div id="section2" class="section toc-section"><a id="sec002" name="sec002" class="link-target" title="Methods"></a> <h3>Methods</h3> <a id="article1.front1.article-meta1.abstract1.sec2.p1" name="article1.front1.article-meta1.abstract1.sec2.p1" class="link-target"></a><p>We followed the PRISMA checklist to present this study. Two experienced review authors (MA and DBK) were systematically searched international electronic databases for studies. We performed meta-analysis using R statistical software. The overall weighted proportion of asymptomatic COVID-19 cases throughout the course infection was computed. The pooled estimates with 95% confidence intervals were presented using forest plot. Egger’s tests were used to assess publication bias, and primary estimates were pooled using a random effects model. Furthermore, a sensitivity analysis was conducted to assure the robustness of the result.</p> </div> <div id="section3" class="section toc-section"><a id="sec003" name="sec003" class="link-target" title="Results"></a> <h3>Results</h3> <a id="article1.front1.article-meta1.abstract1.sec3.p1" name="article1.front1.article-meta1.abstract1.sec3.p1" class="link-target"></a><p>A total of 28 studies that satisfied the eligibility criteria were included in this systematic review and meta-analysis. Consequently, in the meta-analysis, a total of 6,071 COVID-19 cases were included. The proportion of asymptomatic infections among the included studies ranged from 1.4% to 78.3%. The findings of this meta-analysis showed that the weighted pooled proportion of asymptomatic COVID-19 cases throughout the course of infection was 25% (95%CI: 16–38). The leave-one out result also revealed that the weighted pooled average of asymptomatic SARS-CoV-2 infection was between 28% and 31.4%.</p> </div> <div id="section4" class="section toc-section"><a id="sec004" name="sec004" class="link-target" title="Conclusions"></a> <h3>Conclusions</h3> <a id="article1.front1.article-meta1.abstract1.sec4.p1" name="article1.front1.article-meta1.abstract1.sec4.p1" class="link-target"></a><p>In conclusion, one-fourth of SARS-CoV-2 infections are remained asymptomatic throughout the course infection. Scale-up of testing, which targeting high risk populations is recommended to tackle the pandemic.</p> </div> </div></div> <div xmlns:plos="http://plos.org" class="articleinfo"><p><strong>Citation: </strong>Alene M, Yismaw L, Assemie MA, Ketema DB, Mengist B, Kassie B, et al. (2021) Magnitude of asymptomatic COVID-19 cases throughout the course of infection: A systematic review and meta-analysis. PLoS ONE 16(3): e0249090. https://doi.org/10.1371/journal.pone.0249090</p><p><strong>Editor: </strong>Kin On Kwok, Chinese University of Hong Kong, HONG KONG</p><p><strong>Received: </strong>September 8, 2020; <strong>Accepted: </strong>March 11, 2021; <strong>Published: </strong> March 23, 2021</p><p><strong>Copyright: </strong> © 2021 Alene et al. This is an open access article distributed under the terms of the <a href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution License</a>, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.</p><p><strong>Data Availability: </strong>All relevant data are within the manuscript and its <a href="#sec020">Supporting Information</a> files.</p><p><strong>Funding: </strong>The authors received no specific funding for this work.</p><p><strong>Competing interests: </strong> The authors have declared that no competing interests exist.</p><p><strong>Abbreviations: </strong>COVID-19, The 2019 Novel Coronavirus Disease; MERS-CoV, Middle East respiratory syndrome coronavirus; SARS-CoV, Severe Acute Respiratory Syndrome Coronavirus; Sever SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2; WHO, World Health Organization; CI, Confidence Interval</p></div> <div xmlns:plos="http://plos.org" id="section1" class="section toc-section"><a id="sec005" name="sec005" data-toc="sec005" class="link-target" title="Background"></a><h2>Background</h2><a id="article1.body1.sec1.p1" name="article1.body1.sec1.p1" class="link-target"></a><p>The novel coronavirus disease 2019 (“COVID-19”) caused by sever acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now established a global pandemic [<a href="#pone.0249090.ref001" class="ref-tip">1</a>]. The pandemic is a challenge for both developed and developing countries causing huge stress on the healthcare system of all countries [<a href="#pone.0249090.ref002" class="ref-tip">2</a>]. Up to February 20, 2021; there were more-than 110 million total COVID-19 cases with more-than two million deaths, worldwide [<a href="#pone.0249090.ref003" class="ref-tip">3</a>]. As studies reported, the early sign of the COVID-19 is pneumonia [<a href="#pone.0249090.ref004" class="ref-tip">4</a>]. In addition, of COVID-19 patients who developed signs and symptoms, the most frequently reported symptoms was fever followed by cough [<a href="#pone.0249090.ref005" class="ref-tip">5</a>].</p> <a id="article1.body1.sec1.p2" name="article1.body1.sec1.p2" class="link-target"></a><p>Asymptomatic and presymptomatic COVID-19 cases are responsible for potentially significant transmissions, and this makes a challenge to control the pandemic [<a href="#pone.0249090.ref006" class="ref-tip">6</a>]. Approximately, half of individuals with positive test results don’t have any symptoms at the time of testing [<a href="#pone.0249090.ref007" class="ref-tip">7</a>]. Additionally, about one-fifth of SARS-CoV-2 infections are remained asymptomatic throughout the course infection. One study indicated that the viral shedding coronavirus is peaked on before symptom onset [<a href="#pone.0249090.ref008" class="ref-tip">8</a>]. This indicates that a substantial proportion of transmission probably occurred before first symptoms in the primary case. Another studies conducted in Singapore and China revealed that about 6.4%, and 12.6% of COVID-19 cases were attributed to asymptomatic transmission, respectively. Consequently, asymptomatic transmission expected to occur 1–3 days before symptom onset of source patients [<a href="#pone.0249090.ref009" class="ref-tip">9</a>].</p> <a id="article1.body1.sec1.p3" name="article1.body1.sec1.p3" class="link-target"></a><p>The serial interval and incubation period are the two main epidemiological parameters that suggests for presymptomatic transmission of COVID-19. When the average serial interval of COVID-19 is shorter than the average incubation period, some proportion of cases are attributed to presymptomatic transmission [<a href="#pone.0249090.ref010" class="ref-tip">10</a>]. Accordingly, an observational study which aimed to provide the epidemiological parameters of COVID-19 using seven countries data revealed that the mean incubation period and serial interval were 7.44 days and 6.70 days, respectively [<a href="#pone.0249090.ref011" class="ref-tip">11</a>].</p> <a id="article1.body1.sec1.p4" name="article1.body1.sec1.p4" class="link-target"></a><p>Globally, a number of studies were conducted to determine the magnitude of asymptomatic SARS-CoV-2 infection. However, there is a need for more robust and well-designed studies to have relevant public health intervention. Studies vary depending on the number of participants recruited, the type of design employed and the country in which the study conducted [<a href="#pone.0249090.ref012" class="ref-tip">12</a>, <a href="#pone.0249090.ref013" class="ref-tip">13</a>]. Combined findings of existing studies significantly strengthen the quality of evidences for public health practice. Since the biological, clinical and epidemiological characteristics of COVID-19 didn’t well known, this well design and appropriately performed study is needed to have a solid evidence-based intervention. The findings of this study will have a potential role to inform policymakers and stakeholders to combat the pandemic. Thus, this systematic review and meta-analysis aims to determine the pooled magnitude of asymptomatic COVID-19 cases throughout the course of infection using existing evidences.</p> </div> <div xmlns:plos="http://plos.org" id="section2" class="section toc-section"><a id="sec006" name="sec006" data-toc="sec006" class="link-target" title="Methods"></a><h2>Methods</h2> <div id="section1" class="section toc-section"><a id="sec007" name="sec007" class="link-target" title="Searching for studies"></a> <h3>Searching for studies</h3> <a id="article1.body1.sec2.sec1.p1" name="article1.body1.sec2.sec1.p1" class="link-target"></a><p>The study follows the preferred reporting items for systematic review and meta-analysis (PRISMA) to present this study. The search was done by two experienced review authors (MA and MAA) from international electronic databases (Google Scholar, PubMed, Science Direct, Web of Science, and CINAHL). In addition, we searched from the reference lists of the included studies to identify any other studies that may have been missed by our search strategy. We used the following search terms: “magnitude” OR “prevalence” AND “asymptomatic” OR “presymptomatic” OR “silent” AND “transmission” AND “coronavirus OR “COVID-19” OR “novel coronavirus” OR “SARS-CoV-2”. Our search was performed between the 1<sup>st</sup> of June and the 9<sup>th</sup> of December, 2020. Finally, all studies were imported into reference management software (Mendeley desktop).</p> </div> <div id="section2" class="section toc-section"><a id="sec008" name="sec008" class="link-target" title="Inclusion criteria"></a> <h3>Inclusion criteria</h3> <a id="article1.body1.sec2.sec2.p1" name="article1.body1.sec2.sec2.p1" class="link-target"></a><p><strong>Estimates reported</strong>: all observational studies reported the magnitude of asymptomatic COVID-19 cases throughout the course of infection</p> <a id="article1.body1.sec2.sec2.p2" name="article1.body1.sec2.sec2.p2" class="link-target"></a><p><strong>Study setting</strong>: worldwide</p> <a id="article1.body1.sec2.sec2.p3" name="article1.body1.sec2.sec2.p3" class="link-target"></a><p><strong>Population</strong>: all age group</p> <a id="article1.body1.sec2.sec2.p4" name="article1.body1.sec2.sec2.p4" class="link-target"></a><p><strong>Publication status</strong>: all published, and unpublished articles</p> <a id="article1.body1.sec2.sec2.p5" name="article1.body1.sec2.sec2.p5" class="link-target"></a><p><strong>Language</strong>: only studies reporting using English language</p> <a id="article1.body1.sec2.sec2.p6" name="article1.body1.sec2.sec2.p6" class="link-target"></a><p><strong>Publication date</strong>: published from the 1<sup>st</sup> of January to the 9<sup>th</sup> of December, 2020</p> </div> <div id="section3" class="section toc-section"><a id="sec009" name="sec009" class="link-target" title="Exclusion criteria"></a> <h3>Exclusion criteria</h3> <a id="article1.body1.sec2.sec3.p1" name="article1.body1.sec2.sec3.p1" class="link-target"></a><p>Articles that was not report the outcome of interest, case reports and review studies were excluded.</p> </div> <div id="section4" class="section toc-section"><a id="sec010" name="sec010" class="link-target" title="Outcome variable and data extraction"></a> <h3>Outcome variable and data extraction</h3> <a id="article1.body1.sec2.sec4.p1" name="article1.body1.sec2.sec4.p1" class="link-target"></a><p>The outcome variable of this study was the magnitude of true asymptomatic SARS-CoV-2 infection. Asymptomatic SARS-CoV-2 infection is defined as an individual without a history of clinical signs and symptoms throughout the course of infection. Two experienced review authors (MA and LY) extracted all essential data from the included studies using a predesigned data extraction form. The data extraction form organized as; the last name of the first author, the country of the study conducted, data collection period, sample size, magnitude of asymptomatic COVID-19 cases. Any inconsistencies in the data extraction process were decided through discussion involving all authors.</p> </div> <div id="section5" class="section toc-section"><a id="sec011" name="sec011" class="link-target" title="Quality assessment"></a> <h3>Quality assessment</h3> <a id="article1.body1.sec2.sec5.p1" name="article1.body1.sec2.sec5.p1" class="link-target"></a><p>Two review authors (LY and TYB) were assessed the risk of bias of the included articles. The Newcastle Ottawa Scale (NOS) adapted for cross-sectional studies was used to evaluate the quality of studies [<a href="#pone.0249090.ref014" class="ref-tip">14</a>]. This tool organized from three major sections. Consequently, the first section scored on the basis of one to five stars focuses on the methodological quality of each study. The second segment of the tool evaluates the comparability of the study groups with a maximum possibility of two stars to be given. The last section of the tool is concerned with the outcomes and statistical analysis of the included studies with a maximum possibility of three stars to be given. Each author rated the quality of each article. Any inconsistent report between the two reviewers was decided by taking the average score of the two reviewers’. Finally, the assessed articles with a score of less than six out of ten were considered as achieving low quality.</p> </div> <div id="section6" class="section toc-section"><a id="sec012" name="sec012" class="link-target" title="Data processing and analysis"></a> <h3>Data processing and analysis</h3> <a id="article1.body1.sec2.sec6.p1" name="article1.body1.sec2.sec6.p1" class="link-target"></a><p>After extracting all essential data using Microsoft Excel, data were exported to R statistical software for further analysis. In-consistency among the reported magnitude of asymptomatic SARS-CoV-2 infection was assessed using I<sup>2</sup>-index [<a href="#pone.0249090.ref015" class="ref-tip">15</a>]. To estimate the weighted pooled magnitude of asymptomatic COVID-19 cases, a random-effect meta-analysis with an estimation of DerSimonian and Laird method was performed. The publication bias was assessed using a tool known as a funnel plot. Funnel plot asymmetry was also tested by using Egger’s and Beggs’ tests [<a href="#pone.0249090.ref016" class="ref-tip">16</a>]. Furthermore, leave-one-out meta-analysis was conducted to assure the robustness of the result. Leave-one-out analysis involves performing a meta-analysis on each subset of the studies obtained by leaving out exactly one study. This shows how each individual study affects the overall estimate of the rest of the studies.</p> </div> </div> <div xmlns:plos="http://plos.org" id="section3" class="section toc-section"><a id="sec013" name="sec013" data-toc="sec013" class="link-target" title="Results"></a><h2>Results</h2> <div id="section1" class="section toc-section"><a id="sec014" name="sec014" class="link-target" title="Search results"></a> <h3>Search results</h3> <a id="article1.body1.sec3.sec1.p1" name="article1.body1.sec3.sec1.p1" class="link-target"></a><p><strong><a href="#pone-0249090-g001">Fig 1</a>,</strong> shows the flow chart diagram describing the selection of studies included in the systematic review and meta-analysis. Our search resulted with a total of 8,260 studies. Consequently, 134 articles were eligible for screening after excluding duplication. Ninety six articles were excluded after reading the title and abstract. After carefully assessed the text in the included studies, ten articles were removed due to not extractable result and the outcome of interest. Finally, in this study, we included a total of 28 studies that satisfied the eligibility criteria.</p> <a class="link-target" id="pone-0249090-g001" name="pone-0249090-g001"></a><div class="figure" data-doi="10.1371/journal.pone.0249090.g001"><div class="img-box"><a title="Click for larger image" href="article/figure/image?size=medium&id=10.1371/journal.pone.0249090.g001" data-doi="10.1371/journal.pone.0249090" data-uri="10.1371/journal.pone.0249090.g001"><img src="article/figure/image?size=inline&id=10.1371/journal.pone.0249090.g001" alt="thumbnail" class="thumbnail" loading="lazy"></a><div class="expand"></div></div><div class="figure-inline-download"> Download: <ul><li><a href="article/figure/powerpoint?id=10.1371/journal.pone.0249090.g001"><div class="definition-label">PPT</div><div class="definition-description">PowerPoint slide</div></a></li><li><a href="article/figure/image?download&size=large&id=10.1371/journal.pone.0249090.g001"><div class="definition-label">PNG</div><div class="definition-description">larger image</div></a></li><li><a href="article/figure/image?download&size=original&id=10.1371/journal.pone.0249090.g001"><div class="definition-label">TIFF</div><div class="definition-description">original image</div></a></li></ul></div><div class="figcaption"><span>Fig 1. </span> Flow chart diagram describing the selection of studies included in the systematic review and meta-analysis on the magnitude of truly asymptomatic SARS-CoV-2 infection, 2020.</div><p class="caption_target"></p><p class="caption_object"><a href="https://doi.org/10.1371/journal.pone.0249090.g001"> https://doi.org/10.1371/journal.pone.0249090.g001</a></p></div></div> <div id="section2" class="section toc-section"><a id="sec015" name="sec015" class="link-target" title="Description of the included studies"></a> <h3>Description of the included studies</h3> <a id="article1.body1.sec3.sec2.p1" name="article1.body1.sec3.sec2.p1" class="link-target"></a><p>The detail description of the included studies are presented in (<strong><a href="#pone-0249090-t001">Table 1</a></strong>). In this systematic review and meta-analysis, a total of 28 studies with a total COVID-19 cases of 6,071 COVID-19 included. The smallest sample size was 23 [<a href="#pone.0249090.ref017" class="ref-tip">17</a>], while the largest sample size was 712 [<a href="#pone.0249090.ref018" class="ref-tip">18</a>]. Nearly half (48.3%) of the included studies were conducted from China.</p> <a class="link-target" id="pone-0249090-t001" name="pone-0249090-t001"></a><div class="figure" data-doi="10.1371/journal.pone.0249090.t001"><div class="img-box"><a title="Click for larger image" href="article/figure/image?size=medium&id=10.1371/journal.pone.0249090.t001" data-doi="10.1371/journal.pone.0249090" data-uri="10.1371/journal.pone.0249090.t001"><img src="article/figure/image?size=inline&id=10.1371/journal.pone.0249090.t001" alt="thumbnail" class="thumbnail" loading="lazy"></a><div class="expand"></div></div><div class="figure-inline-download"> Download: <ul><li><a href="article/figure/powerpoint?id=10.1371/journal.pone.0249090.t001"><div class="definition-label">PPT</div><div class="definition-description">PowerPoint slide</div></a></li><li><a href="article/figure/image?download&size=large&id=10.1371/journal.pone.0249090.t001"><div class="definition-label">PNG</div><div class="definition-description">larger image</div></a></li><li><a href="article/figure/image?download&size=original&id=10.1371/journal.pone.0249090.t001"><div class="definition-label">TIFF</div><div class="definition-description">original image</div></a></li></ul></div><div class="figcaption"><span>Table 1. </span> Descriptions of the included studies conducted on the proportion of asymptomatic SARS-CoV-2 infection, 2020.</div><p class="caption_target"></p><p class="caption_object"><a href="https://doi.org/10.1371/journal.pone.0249090.t001"> https://doi.org/10.1371/journal.pone.0249090.t001</a></p></div></div> <div id="section3" class="section toc-section"><a id="sec016" name="sec016" class="link-target" title="Magnitude of asymptomatic COVID-19 cases"></a> <h3>Magnitude of asymptomatic COVID-19 cases</h3> <a id="article1.body1.sec3.sec3.p1" name="article1.body1.sec3.sec3.p1" class="link-target"></a><p>Of the included studies, the proportion of asymptomatic SARS-CoV-2 infections ranged from 1% to 81%. Consequently, our meta-analysis showed that the weighted pooled truly asymptomatic COVID-19 cases was 25% (95%CI: 16–38) (<strong><a href="#pone-0249090-g002">Fig 2</a></strong>). <strong><a href="#pone-0249090-t002">Table 2</a>,</strong> shows the sensitivity analysis of the study. The minimum weighted pooled proportion (28%) of SARS-CoV-2 was found by removing article [<a href="#pone.0249090.ref022" class="ref-tip">22</a>], while the maximum proportion (31.4%) was obtained after removing the study [<a href="#pone.0249090.ref028" class="ref-tip">28</a>]. The issue of publication bias was assessed by graphic inspection of funnel plot and using the rank correlation test. Even though, the funnel plot looks asymmetrical (<strong><a href="#pone-0249090-g003">Fig 3</a></strong>), the rank correlation test showed that no relationship between the effect size and its precision (P-value = 0.4).</p> <a class="link-target" id="pone-0249090-g002" name="pone-0249090-g002"></a><div class="figure" data-doi="10.1371/journal.pone.0249090.g002"><div class="img-box"><a title="Click for larger image" href="article/figure/image?size=medium&id=10.1371/journal.pone.0249090.g002" data-doi="10.1371/journal.pone.0249090" data-uri="10.1371/journal.pone.0249090.g002"><img src="article/figure/image?size=inline&id=10.1371/journal.pone.0249090.g002" alt="thumbnail" class="thumbnail" loading="lazy"></a><div class="expand"></div></div><div class="figure-inline-download"> Download: <ul><li><a href="article/figure/powerpoint?id=10.1371/journal.pone.0249090.g002"><div class="definition-label">PPT</div><div class="definition-description">PowerPoint slide</div></a></li><li><a href="article/figure/image?download&size=large&id=10.1371/journal.pone.0249090.g002"><div class="definition-label">PNG</div><div class="definition-description">larger image</div></a></li><li><a href="article/figure/image?download&size=original&id=10.1371/journal.pone.0249090.g002"><div class="definition-label">TIFF</div><div class="definition-description">original image</div></a></li></ul></div><div class="figcaption"><span>Fig 2. </span> Forest plot that shows the weighted pooled proportion of asymptomatic SARS-CoV-2 infection using available studies, 2020.</div><p class="caption_target"></p><p class="caption_object"><a href="https://doi.org/10.1371/journal.pone.0249090.g002"> https://doi.org/10.1371/journal.pone.0249090.g002</a></p></div><a class="link-target" id="pone-0249090-g003" name="pone-0249090-g003"></a><div class="figure" data-doi="10.1371/journal.pone.0249090.g003"><div class="img-box"><a title="Click for larger image" href="article/figure/image?size=medium&id=10.1371/journal.pone.0249090.g003" data-doi="10.1371/journal.pone.0249090" data-uri="10.1371/journal.pone.0249090.g003"><img src="article/figure/image?size=inline&id=10.1371/journal.pone.0249090.g003" alt="thumbnail" class="thumbnail" loading="lazy"></a><div class="expand"></div></div><div class="figure-inline-download"> Download: <ul><li><a href="article/figure/powerpoint?id=10.1371/journal.pone.0249090.g003"><div class="definition-label">PPT</div><div class="definition-description">PowerPoint slide</div></a></li><li><a href="article/figure/image?download&size=large&id=10.1371/journal.pone.0249090.g003"><div class="definition-label">PNG</div><div class="definition-description">larger image</div></a></li><li><a href="article/figure/image?download&size=original&id=10.1371/journal.pone.0249090.g003"><div class="definition-label">TIFF</div><div class="definition-description">original image</div></a></li></ul></div><div class="figcaption"><span>Fig 3. </span> Funnel plot to check the publication bias of the included studies conducted on truly asymptomatic SARS-CoV-2 infection, 2020.</div><p class="caption_target"></p><p class="caption_object"><a href="https://doi.org/10.1371/journal.pone.0249090.g003"> https://doi.org/10.1371/journal.pone.0249090.g003</a></p></div><a class="link-target" id="pone-0249090-t002" name="pone-0249090-t002"></a><div class="figure" data-doi="10.1371/journal.pone.0249090.t002"><div class="img-box"><a title="Click for larger image" href="article/figure/image?size=medium&id=10.1371/journal.pone.0249090.t002" data-doi="10.1371/journal.pone.0249090" data-uri="10.1371/journal.pone.0249090.t002"><img src="article/figure/image?size=inline&id=10.1371/journal.pone.0249090.t002" alt="thumbnail" class="thumbnail" loading="lazy"></a><div class="expand"></div></div><div class="figure-inline-download"> Download: <ul><li><a href="article/figure/powerpoint?id=10.1371/journal.pone.0249090.t002"><div class="definition-label">PPT</div><div class="definition-description">PowerPoint slide</div></a></li><li><a href="article/figure/image?download&size=large&id=10.1371/journal.pone.0249090.t002"><div class="definition-label">PNG</div><div class="definition-description">larger image</div></a></li><li><a href="article/figure/image?download&size=original&id=10.1371/journal.pone.0249090.t002"><div class="definition-label">TIFF</div><div class="definition-description">original image</div></a></li></ul></div><div class="figcaption"><span>Table 2. </span> The sensitivity analysis to estimate the pooled proportion of truly asymptomatic SARS-CoV-2 infection, 2020.</div><p class="caption_target"></p><p class="caption_object"><a href="https://doi.org/10.1371/journal.pone.0249090.t002"> https://doi.org/10.1371/journal.pone.0249090.t002</a></p></div></div> </div> <div xmlns:plos="http://plos.org" id="section4" class="section toc-section"><a id="sec017" name="sec017" data-toc="sec017" class="link-target" title="Discussion"></a><h2>Discussion</h2><a id="article1.body1.sec4.p1" name="article1.body1.sec4.p1" class="link-target"></a><p>COVID-19 pandemic remains a major public health problem worldwide. Currently, there is no enough evidences to recommend any specific medication for the treatment of COVID-19. Presymptomatic and asymptomatic SARS-CoV-2 infections are capable to transmitting the virus, and this makes challenging to prevent and control the pandemic. Previous evidences showed that SARS-CoV-2 infections are spread more rapidly compared with Sever Acute Respiratory Syndrome Coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) [<a href="#pone.0249090.ref045" class="ref-tip">45</a>]. Previous studies suggest that contact and symptom based screening might fail to identify all potential SARS-CoV-2 infections. The current study was aimed to determine the overall magnitude of asymptomatic COVID-19 cases throughout the course of infection.</p> <a id="article1.body1.sec4.p2" name="article1.body1.sec4.p2" class="link-target"></a><p>We computed the overall weighted proportion of COVID-19 cases who hadn’t developed signs and symptoms throughout the course of infection. Accordingly, one-fourth (25% (95%CI: 16–38)) of COVID-19 cases were asymptomatic throughout the course of infection. This result is comparable with previous study conducted on the asymptomatic SARS-CoV-infections. However, this result is lower than previous studies conducted on asymptomatic SARS-CoV-2 infection [<a href="#pone.0249090.ref006" class="ref-tip">6</a>, <a href="#pone.0249090.ref007" class="ref-tip">7</a>]. The possible reason for this variation might be asymptomatic COVID-19 cases considered in the previous studies will develop sign and symptoms during hospitalization period. A study conducted in Barcelona, Spain revealed that more-than two-third of SRAS-CoV-2 infections are asymptomatic at the time of testing [<a href="#pone.0249090.ref046" class="ref-tip">46</a>].</p> <a id="article1.body1.sec4.p3" name="article1.body1.sec4.p3" class="link-target"></a><p>We also compared the proportion of asymptomatic SARS-CoV-2 infections with previously emerged coronavirus outbreaks. A study that reports the role of asymptomatic patients in the transmission of MERS-CoV showed that one-fourth (25.1%) of MERS-CoV were asymptomatic [<a href="#pone.0249090.ref047" class="ref-tip">47</a>]. Though, one study showed that small number of SARS-CoV cases are asymptomatic, unlike COVID-19, sever acute respiratory syndrome could be controlled by effective isolation of symptomatic patients [<a href="#pone.0249090.ref048" class="ref-tip">48</a>]. One study also showed that nearly half of SARS-CoV patients were asymptomatic throughout the course hospitalization [<a href="#pone.0249090.ref049" class="ref-tip">49</a>]. This inconsistency might be due to the difference in clinical severity between COVID-19 cases, MERS and SARS-CoV [<a href="#pone.0249090.ref050" class="ref-tip">50</a>].</p> <div id="section1" class="section toc-section"><a id="sec018" name="sec018" class="link-target" title="Limitation"></a> <h3>Limitation</h3> <a id="article1.body1.sec4.sec1.p1" name="article1.body1.sec4.sec1.p1" class="link-target"></a><p>The current study has a number of limitations. Firstly, the majority of the included studies had relatively small sample size which may decrease the power of the study. Secondly, the review was limited to only articles published in the English language. Lastly, since the included articles are limited to few countries, it may not represent the global figure of asymptomatic SARS-CoV-2 infection.</p> </div> </div> <div xmlns:plos="http://plos.org" id="section5" class="section toc-section"><a id="sec019" name="sec019" data-toc="sec019" class="link-target" title="Conclusions"></a><h2>Conclusions</h2><a id="article1.body1.sec5.p1" name="article1.body1.sec5.p1" class="link-target"></a><p>In conclusion, one-fourth of SARS-CoV-2 infections are remained asymptomatic throughout the course infection. Scale-up of testing, which targeting high risk populations is recommended to tackle the pandemic.</p> </div> <div xmlns:plos="http://plos.org" id="section6" class="section toc-section"><a id="sec020" name="sec020" data-toc="sec020" class="link-target" title="Supporting information"></a><h2>Supporting information</h2><div class="figshare_widget" doi="10.1371/journal.pone.0249090"></div><div class="supplementary-material"><a name="pone.0249090.s001" id="pone.0249090.s001" class="link-target"></a><h3 class="siTitle title-small"><a href="article/file?type=supplementary&id=10.1371/journal.pone.0249090.s001">S1 Checklist. </a>PRISMA 2009 checklist.</h3><p class="siDoi"><a href="https://doi.org/10.1371/journal.pone.0249090.s001">https://doi.org/10.1371/journal.pone.0249090.s001</a></p><a id="article1.body1.sec6.supplementary-material1.caption1.p1" name="article1.body1.sec6.supplementary-material1.caption1.p1" class="link-target"></a><p class="postSiDOI">(DOC)</p> </div><div class="supplementary-material"><a name="pone.0249090.s002" id="pone.0249090.s002" class="link-target"></a><h3 class="siTitle title-small"><a href="article/file?type=supplementary&id=10.1371/journal.pone.0249090.s002">S1 Table. </a>Individual effect sizes of the included studies conducted on truly asymptomatic SARS-CoV-2 infection, 2020.</h3><p class="siDoi"><a href="https://doi.org/10.1371/journal.pone.0249090.s002">https://doi.org/10.1371/journal.pone.0249090.s002</a></p><a id="article1.body1.sec6.supplementary-material2.caption1.p1" name="article1.body1.sec6.supplementary-material2.caption1.p1" class="link-target"></a><p class="postSiDOI">(DOCX)</p> </div></div> <div xmlns:plos="http://plos.org" class="toc-section"><a id="references" name="references" class="link-target" data-toc="references" title="References"></a><h2>References</h2><ol class="references"><li id="ref1"><span class="order">1. </span><a name="pone.0249090.ref001" id="pone.0249090.ref001" class="link-target"></a>WHO. media briefing on COVID-19–11 March 2020. Accessed from <a href="https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19%E2%80%9411-march-2020">https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19—11-march-2020</a>. <ul class="find-nolinks"></ul></li><li id="ref2"><span class="order">2. </span><a name="pone.0249090.ref002" id="pone.0249090.ref002" class="link-target"></a>The world bank.The Global Economic Outlook During the COVID-19 Pandemic: A Changed World,June 8,2020. accessed from <a href="https://www.worldbank.org/en/news/feature/2020/06/08/the-global-economic-outlook-during-the-covid-19-pandemic-a-changed-world">https://www.worldbank.org/en/news/feature/2020/06/08/the-global-economic-outlook-during-the-covid-19-pandemic-a-changed-world</a>. <ul class="reflinks"><li><a href="#" data-author="" data-cit="The%20world%20bank.The%20Global%20Economic%20Outlook%20During%20the%20COVID-19%20Pandemic%3A%20A%20Changed%20World%2CJune%208%2C2020.%20accessed%20from%20https%3A%2F%2Fwww.worldbank.org%2Fen%2Fnews%2Ffeature%2F2020%2F06%2F08%2Fthe-global-economic-outlook-during-the-covid-19-pandemic-a-changed-world." data-title="The%20Global%20Economic%20Outlook%20During%20the%20COVID-19%20Pandemic%3A%20A%20Changed%20World" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=The+Global+Economic+Outlook+During+the+COVID-19+Pandemic%3A+A+Changed+World++2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref3"><span class="order">3. </span><a name="pone.0249090.ref003" id="pone.0249090.ref003" class="link-target"></a>JHONS HOPKINS coronavirus resource center.COVID-19. Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU). <ul class="find-nolinks"></ul></li><li id="ref4"><span class="order">4. </span><a name="pone.0249090.ref004" id="pone.0249090.ref004" class="link-target"></a>Rafiq D, Batool A, Bazaz MA. Three months of COVID‐19: A systematic review and meta‐analysis. Reviews in Medical Virology. 2020 May 18:e2113. pmid:32420674 <ul class="reflinks" data-doi="10.1002/rmv.2113"><li><a href="https://doi.org/10.1002/rmv.2113" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32420674" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Three+months+of+COVID%E2%80%9019%3A+A+systematic+review+and+meta%E2%80%90analysis+Rafiq+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref5"><span class="order">5. </span><a name="pone.0249090.ref005" id="pone.0249090.ref005" class="link-target"></a>Grant MC, Geoghegan L, Arbyn M, Mohammed Z, McGuinness L, Clarke EL, et al. The Prevalence of Symptoms in 24,410 Adults Infected by the Novel Coronavirus (SARS-CoV-2; COVID-19): A Systematic Review and Meta-Analysis of 148 Studies from 9 Countries. Avail. pmid:32574165 <ul class="reflinks" data-doi="10.1371/journal.pone.0234765"><li><a href="https://doi.org/10.1371/journal.pone.0234765" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32574165" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=The+Prevalence+of+Symptoms+in+24%2C410+Adults+Infected+by+the+Novel+Coronavirus+%28SARS-CoV-2%3B+COVID-19%29%3A+A+Systematic+Review+and+Meta-Analysis+of+148+Studies+from+9+Countries+Grant+" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref6"><span class="order">6. </span><a name="pone.0249090.ref006" id="pone.0249090.ref006" class="link-target"></a>Kronbichler A, Kresse D, Yoon S, Lee KH, Effenberger M, Shin JI. Asymptomatic patients as a source of COVID-19 infections: A systematic review and meta-analysis. International Journal of Infectious Diseases. 2020 Jun 17. pmid:32562846 <ul class="reflinks" data-doi="10.1016/j.ijid.2020.06.052"><li><a href="https://doi.org/10.1016/j.ijid.2020.06.052" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32562846" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+patients+as+a+source+of+COVID-19+infections%3A+A+systematic+review+and+meta-analysis+Kronbichler+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref7"><span class="order">7. </span><a name="pone.0249090.ref007" id="pone.0249090.ref007" class="link-target"></a>Syangtan G, Bista S, Dawadi P, Rayamajhee B, Shrestha LB, Tuladhar R, et al. Asymptomatic people with SARS-CoV-2 as unseen carriers of COVID-19: A systematic review and meta-analysis. <ul class="reflinks"><li><a href="#" data-author="Syangtan" data-cit="SyangtanG%2C%20BistaS%2C%20DawadiP%2C%20RayamajheeB%2C%20ShresthaLB%2C%20TuladharR%2C%20et%20al.%20Asymptomatic%20people%20with%20SARS-CoV-2%20as%20unseen%20carriers%20of%20COVID-19%3A%20A%20systematic%20review%20and%20meta-analysis." data-title="Asymptomatic%20people%20with%20SARS-CoV-2%20as%20unseen%20carriers%20of%20COVID-19%3A%20A%20systematic%20review%20and%20meta-analysis" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+people+with+SARS-CoV-2+as+unseen+carriers+of+COVID-19%3A+A+systematic+review+and+meta-analysis+Syangtan+" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref8"><span class="order">8. </span><a name="pone.0249090.ref008" id="pone.0249090.ref008" class="link-target"></a>He X, Lau EH, Wu P, Deng X, Wang J, Hao X, et al. Temporal dynamics in viral shedding and transmissibility of COVID-19. Nature medicine. 2020 May;26(5):672–5. pmid:32296168 <ul class="reflinks" data-doi="10.1038/s41591-020-0869-5"><li><a href="https://doi.org/10.1038/s41591-020-0869-5" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32296168" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Temporal+dynamics+in+viral+shedding+and+transmissibility+of+COVID-19+He+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref9"><span class="order">9. </span><a name="pone.0249090.ref009" id="pone.0249090.ref009" class="link-target"></a>Wei WE, Li Z, Chiew CJ, Yong SE, Toh MP, Lee VJ. Presymptomatic Transmission of SARS-CoV-2—Singapore, January 23–March 16, 2020. Morbidity and Mortality Weekly Report. 2020 Apr 10;69(14):411. pmid:32271722 <ul class="reflinks" data-doi="10.15585/mmwr.mm6914e1"><li><a href="https://doi.org/10.15585/mmwr.mm6914e1" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32271722" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Presymptomatic+Transmission+of+SARS-CoV-2%E2%80%94Singapore%2C+January+23%E2%80%93March+16%2C+2020+Wei+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref10"><span class="order">10. </span><a name="pone.0249090.ref010" id="pone.0249090.ref010" class="link-target"></a>Du Z, Xu X, Wu Y, Wang L, Cowling BJ, Meyers LA. Serial interval of COVID-19 among publicly reported confirmed cases. Emerging infectious diseases. 2020 Jun;26(6):1341. pmid:32191173 <ul class="reflinks" data-doi="10.3201/eid2606.200357"><li><a href="https://doi.org/10.3201/eid2606.200357" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32191173" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Serial+interval+of+COVID-19+among+publicly+reported+confirmed+cases+Du+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref11"><span class="order">11. </span><a name="pone.0249090.ref011" id="pone.0249090.ref011" class="link-target"></a>Ma S, Zhang J, Zeng M, Yun Q, Guo W, Zheng Y, et al. Epidemiological parameters of coronavirus disease 2019: a pooled analysis of publicly reported individual data of 1155 cases from seven countries. Medrxiv. 2020 Jan 1. <ul class="reflinks"><li><a href="#" data-author="Ma" data-cit="MaS%2C%20ZhangJ%2C%20ZengM%2C%20YunQ%2C%20GuoW%2C%20ZhengY%2C%20et%20al.%20Epidemiological%20parameters%20of%20coronavirus%20disease%202019%3A%20a%20pooled%20analysis%20of%20publicly%20reported%20individual%20data%20of%201155%20cases%20from%20seven%20countries.%20Medrxiv.%202020%20Jan%201." data-title="Epidemiological%20parameters%20of%20coronavirus%20disease%202019%3A%20a%20pooled%20analysis%20of%20publicly%20reported%20individual%20data%20of%201155%20cases%20from%20seven%20countries" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Epidemiological+parameters+of+coronavirus+disease+2019%3A+a+pooled+analysis+of+publicly+reported+individual+data+of+1155+cases+from+seven+countries+Ma+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref12"><span class="order">12. </span><a name="pone.0249090.ref012" id="pone.0249090.ref012" class="link-target"></a>Alene M, Yismaw L, Berelie Y, Kassie B, Yeshambel R, Assemie MA. Prevalence and determinants of unintended pregnancy in Ethiopia: A systematic review and meta-analysis of observational studies. PloS one. 2020 Apr 7;15(4):e0231012. pmid:32255774 <ul class="reflinks" data-doi="10.1371/journal.pone.0231012"><li><a href="https://doi.org/10.1371/journal.pone.0231012" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32255774" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=PloS+one.+Alene+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref13"><span class="order">13. </span><a name="pone.0249090.ref013" id="pone.0249090.ref013" class="link-target"></a>Alene M, Assemie MA, Yismaw L, Gedif G, Ketema DB, Gietaneh W, et al. Patient delay in the diagnosis of tuberculosis in Ethiopia: a systematic review and meta-analysis. BMC infectious diseases. 2020 Dec;20(1):1–9. <ul class="reflinks"><li><a href="#" data-author="Alene" data-cit="AleneM%2C%20AssemieMA%2C%20YismawL%2C%20GedifG%2C%20KetemaDB%2C%20GietanehW%2C%20et%20al.%20Patient%20delay%20in%20the%20diagnosis%20of%20tuberculosis%20in%20Ethiopia%3A%20a%20systematic%20review%20and%20meta-analysis.%20BMC%20infectious%20diseases.%202020%20Dec%3B20%281%29%3A1%E2%80%939." data-title="Patient%20delay%20in%20the%20diagnosis%20of%20tuberculosis%20in%20Ethiopia%3A%20a%20systematic%20review%20and%20meta-analysis" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Patient+delay+in+the+diagnosis+of+tuberculosis+in+Ethiopia%3A+a+systematic+review+and+meta-analysis+Alene+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref14"><span class="order">14. </span><a name="pone.0249090.ref014" id="pone.0249090.ref014" class="link-target"></a>Newcastle-Ottawa Scale customized for cross-sectional studies In. available from <a href="https://static-content.springer.com/esm/%E2%80%A6/12889_2012_5111_MOESM3_ESM.doc">https://static-content.springer.com/esm/…/12889_2012_5111_MOESM3_ESM.doc</a>. <ul class="find-nolinks"></ul></li><li id="ref15"><span class="order">15. </span><a name="pone.0249090.ref015" id="pone.0249090.ref015" class="link-target"></a>Melsen WG, Bootsma MC, Rovers MM, Bonten MJ. The effects of clinical and statistical heterogeneity on the predictive values of results from meta-analyses. Clinical Microbiology and Infection. 2014 Feb 1;20(2):123–9. pmid:24320992 <ul class="reflinks" data-doi="10.1111/1469-0691.12494"><li><a href="https://doi.org/10.1111/1469-0691.12494" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/24320992" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=The+effects+of+clinical+and+statistical+heterogeneity+on+the+predictive+values+of+results+from+meta-analyses+Melsen+2014" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref16"><span class="order">16. </span><a name="pone.0249090.ref016" id="pone.0249090.ref016" class="link-target"></a>van Enst WA, Ochodo E, Scholten RJ, Hooft L, Leeflang MM. Investigation of publication bias in meta-analyses of diagnostic test accuracy: a meta-epidemiological study. BMC medical research methodology. 2014 Dec 1;14(1):70. pmid:24884381 <ul class="reflinks" data-doi="10.1186/1471-2288-14-70"><li><a href="https://doi.org/10.1186/1471-2288-14-70" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/24884381" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Investigation+of+publication+bias+in+meta-analyses+of+diagnostic+test+accuracy%3A+a+meta-epidemiological+study+van+Enst+2014" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref17"><span class="order">17. </span><a name="pone.0249090.ref017" id="pone.0249090.ref017" class="link-target"></a>Kimball A, Hatfield KM, Arons M, James A, Taylor J, Spicer K, et al. Asymptomatic and presymptomatic SARS-CoV-2 infections in residents of a long-term care skilled nursing facility—King County, Washington, Mar. <ul class="reflinks"><li><a href="#" data-author="Kimball" data-cit="KimballA%2C%20HatfieldKM%2C%20AronsM%2C%20JamesA%2C%20TaylorJ%2C%20SpicerK%2C%20et%20al.%20Asymptomatic%20and%20presymptomatic%20SARS-CoV-2%20infections%20in%20residents%20of%20a%20long-term%20care%20skilled%20nursing%20facility%E2%80%94King%20County%2C%20Washington%2C%20Mar." data-title="Asymptomatic%20and%20presymptomatic%20SARS-CoV-2%20infections%20in%20residents%20of%20a%20long-term%20care%20skilled%20nursing%20facility%E2%80%94King%20County%2C%20Washington" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+and+presymptomatic+SARS-CoV-2+infections+in+residents+of+a+long-term+care+skilled+nursing+facility%E2%80%94King+County%2C+Washington+Kimball+" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref18"><span class="order">18. </span><a name="pone.0249090.ref018" id="pone.0249090.ref018" class="link-target"></a>Moriarty LF. Public health responses to COVID-19 outbreaks on cruise ships—worldwide, February–March 2020. MMWR. Morbidity and mortality weekly report. 2020;69. pmid:32214086 <ul class="reflinks" data-doi="10.15585/mmwr.mm6912e3"><li><a href="https://doi.org/10.15585/mmwr.mm6912e3" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32214086" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Public+health+responses+to+COVID-19+outbreaks+on+cruise+ships%E2%80%94worldwide%2C+February%E2%80%93March+2020+Moriarty+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref19"><span class="order">19. </span><a name="pone.0249090.ref019" id="pone.0249090.ref019" class="link-target"></a>An P, Song P, Wang Y, Liu B. Asymptomatic patients with novel coronavirus disease (COVID-19). Blood. 2020 Apr 13;3:12–0. <ul class="reflinks"><li><a href="#" data-author="An" data-cit="AnP%2C%20SongP%2C%20WangY%2C%20LiuB.%20Asymptomatic%20patients%20with%20novel%20coronavirus%20disease%20%28COVID-19%29.%20Blood.%202020%20Apr%2013%3B3%3A12%E2%80%930." data-title="Asymptomatic%20patients%20with%20novel%20coronavirus%20disease%20%28COVID-19%29" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+patients+with+novel+coronavirus+disease+%28COVID-19%29+An+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref20"><span class="order">20. </span><a name="pone.0249090.ref020" id="pone.0249090.ref020" class="link-target"></a>Arons MM, Hatfield KM, Reddy SC, Kimball A, James A, Jacobs JR, et al. Presymptomatic SARS-CoV-2 infections and transmission in a skilled nursing facility. New England journal of medicine. 2020 Apr 24. <ul class="reflinks"><li><a href="#" data-author="Arons" data-cit="AronsMM%2C%20HatfieldKM%2C%20ReddySC%2C%20KimballA%2C%20JamesA%2C%20JacobsJR%2C%20et%20al.%20Presymptomatic%20SARS-CoV-2%20infections%20and%20transmission%20in%20a%20skilled%20nursing%20facility.%20New%20England%20journal%20of%20medicine.%202020%20Apr%2024." data-title="Presymptomatic%20SARS-CoV-2%20infections%20and%20transmission%20in%20a%20skilled%20nursing%20facility" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Presymptomatic+SARS-CoV-2+infections+and+transmission+in+a+skilled+nursing+facility+Arons+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref21"><span class="order">21. </span><a name="pone.0249090.ref021" id="pone.0249090.ref021" class="link-target"></a>Chun JY, Baek G, Kim Y. Transmission onset distribution of COVID-19 in South Korea. medRxiv. 2020 Jan 1. <ul class="reflinks"><li><a href="#" data-author="Chun" data-cit="ChunJY%2C%20BaekG%2C%20KimY.%20Transmission%20onset%20distribution%20of%20COVID-19%20in%20South%20Korea.%20medRxiv.%202020%20Jan%201." data-title="Transmission%20onset%20distribution%20of%20COVID-19%20in%20South%20Korea" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Transmission+onset+distribution+of+COVID-19+in+South+Korea+Chun+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref22"><span class="order">22. </span><a name="pone.0249090.ref022" id="pone.0249090.ref022" class="link-target"></a>Day M. Covid-19: four fifths of cases are asymptomatic, China figures indicate. <ul class="reflinks"><li><a href="#" data-author="Day" data-cit="DayM.%20Covid-19%3A%20four%20fifths%20of%20cases%20are%20asymptomatic%2C%20China%20figures%20indicate." data-title="Covid-19%3A%20four%20fifths%20of%20cases%20are%20asymptomatic%2C%20China%20figures%20indicate" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Covid-19%3A+four+fifths+of+cases+are+asymptomatic%2C+China+figures+indicate+Day+" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref23"><span class="order">23. </span><a name="pone.0249090.ref023" id="pone.0249090.ref023" class="link-target"></a>Feaster M, Goh YY. High Proportion of Asymptomatic SARS-CoV-2 Infections in 9 Long-Term Care Facilities, Pasadena, California, USA, April 2020. Emerging Infectious Diseases. 2020 Jul 2;26(10). <ul class="reflinks"><li><a href="#" data-author="Feaster" data-cit="FeasterM%2C%20GohYY.%20High%20Proportion%20of%20Asymptomatic%20SARS-CoV-2%20Infections%20in%209%20Long-Term%20Care%20Facilities%2C%20Pasadena%2C%20California%2C%20USA%2C%20April%202020.%20Emerging%20Infectious%20Diseases.%202020%20Jul%202%3B26%2810%29." data-title="High%20Proportion%20of%20Asymptomatic%20SARS-CoV-2%20Infections%20in%209%20Long-Term%20Care%20Facilities%2C%20Pasadena%2C%20California%2C%20USA%2C%20April%202020" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=High+Proportion+of+Asymptomatic+SARS-CoV-2+Infections+in+9+Long-Term+Care+Facilities%2C+Pasadena%2C+California%2C+USA%2C+April+2020+Feaster+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref24"><span class="order">24. </span><a name="pone.0249090.ref024" id="pone.0249090.ref024" class="link-target"></a>Inui S, Fujikawa A, Jitsu M, Kunishima N, Watanabe S, Suzuki Y, et al. Chest CT findings in cases from the cruise ship “Diamond Princess” with coronavirus disease 2019 (COVID-19). Radiology: Cardiothoracic Imaging. 2020 Mar 17;2(2):e200110. <ul class="reflinks"><li><a href="#" data-author="Inui" data-cit="InuiS%2C%20FujikawaA%2C%20JitsuM%2C%20KunishimaN%2C%20WatanabeS%2C%20SuzukiY%2C%20et%20al.%20Chest%20CT%20findings%20in%20cases%20from%20the%20cruise%20ship%20%E2%80%9CDiamond%20Princess%E2%80%9D%20with%20coronavirus%20disease%202019%20%28COVID-19%29.%20Radiology%3A%20Cardiothoracic%20Imaging.%202020%20Mar%2017%3B2%282%29%3Ae200110." data-title="Chest%20CT%20findings%20in%20cases%20from%20the%20cruise%20ship%20%E2%80%9CDiamond%20Princess%E2%80%9D%20with%20coronavirus%20disease%202019%20%28COVID-19%29" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Chest+CT+findings+in+cases+from+the+cruise+ship+%E2%80%9CDiamond+Princess%E2%80%9D+with+coronavirus+disease+2019+%28COVID-19%29+Inui+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref25"><span class="order">25. </span><a name="pone.0249090.ref025" id="pone.0249090.ref025" class="link-target"></a>Keeley AJ, Evans CM, De Silva TI. Asymptomatic SARS-CoV-2 infection: the tip or the iceberg?. Thorax. 2020 Aug 1;75(8):621–2. pmid:32580993 <ul class="reflinks" data-doi="10.1136/thoraxjnl-2020-215337"><li><a href="https://doi.org/10.1136/thoraxjnl-2020-215337" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32580993" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+SARS-CoV-2+infection%3A+the+tip+or+the+iceberg%3F+Keeley+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref26"><span class="order">26. </span><a name="pone.0249090.ref026" id="pone.0249090.ref026" class="link-target"></a>Kong W, Wang Y, Hu J, Chughtai A, Pu H, of Sichuan CR. Comparison of clinical and epidemiological characteristics of asymptomatic and symptomatic SARS-CoV-2 infection: A multi-center study in Sichuan Province, China. Travel Medicine and Infectious Disease. pmid:32492485 <ul class="reflinks" data-doi="10.1016/j.tmaid.2020.101754"><li><a href="https://doi.org/10.1016/j.tmaid.2020.101754" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32492485" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Comparison+of+clinical+and+epidemiological+characteristics+of+asymptomatic+and+symptomatic+SARS-CoV-2+infection%3A+A+multi-center+study+in+Sichuan+Province%2C+China+Kong+" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref27"><span class="order">27. </span><a name="pone.0249090.ref027" id="pone.0249090.ref027" class="link-target"></a>Lavezzo E, Franchin E, Ciavarella C, Cuomo-Dannenburg G, Barzon L, Del Vecchio C, et al. Suppression of COVID-19 outbreak in the municipality of Vo, Italy. medRxiv. 2020 Jan 1. <ul class="reflinks"><li><a href="#" data-author="Lavezzo" data-cit="LavezzoE%2C%20FranchinE%2C%20CiavarellaC%2C%20Cuomo-DannenburgG%2C%20BarzonL%2C%20Del%20VecchioC%2C%20et%20al.%20Suppression%20of%20COVID-19%20outbreak%20in%20the%20municipality%20of%20Vo%2C%20Italy.%20medRxiv.%202020%20Jan%201." data-title="Suppression%20of%20COVID-19%20outbreak%20in%20the%20municipality%20of%20Vo%2C%20Italy" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Suppression+of+COVID-19+outbreak+in+the+municipality+of+Vo%2C+Italy+Lavezzo+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref28"><span class="order">28. </span><a name="pone.0249090.ref028" id="pone.0249090.ref028" class="link-target"></a>Ling Z, Xu X, Gan Q, Zhang L, Luo L, Tang X, et al. Asymptomatic SARS-CoV-2 infected patients with persistent negative CT findings. European journal of radiology. 2020 May 1;126. pmid:32199142 <ul class="reflinks" data-doi="10.1016/j.ejrad.2020.108956"><li><a href="https://doi.org/10.1016/j.ejrad.2020.108956" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32199142" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+SARS-CoV-2+infected+patients+with+persistent+negative+CT+findings+Ling+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref29"><span class="order">29. </span><a name="pone.0249090.ref029" id="pone.0249090.ref029" class="link-target"></a>Long QX, Tang XJ, Shi QL, Li Q, Deng HJ, Yuan J, et al. Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections. Nature medicine. 2020 Jun 18:1–5. pmid:32555424 <ul class="reflinks" data-doi="10.1038/s41591-020-0965-6"><li><a href="https://doi.org/10.1038/s41591-020-0965-6" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32555424" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Clinical+and+immunological+assessment+of+asymptomatic+SARS-CoV-2+infections+Long+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref30"><span class="order">30. </span><a name="pone.0249090.ref030" id="pone.0249090.ref030" class="link-target"></a>Luo SH, Liu W, Liu ZJ, Zheng XY, Hong CX, Liu ZR, et al. A confirmed asymptomatic carrier of 2019 novel coronavirus. Chinese medical journal. 2020 May 5;133(9):1123–5. pmid:32149768 <ul class="reflinks" data-doi="10.1097/CM9.0000000000000798"><li><a href="https://doi.org/10.1097/CM9.0000000000000798" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32149768" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=A+confirmed+asymptomatic+carrier+of+2019+novel+coronavirus+Luo+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref31"><span class="order">31. </span><a name="pone.0249090.ref031" id="pone.0249090.ref031" class="link-target"></a>Ma Y, Xu QN, Wang FL, Ma XM, Wang XY, Zhang XG, et al. Characteristics of asymptomatic patients with SARS-CoV-2 infection in Jinan, China. Microbes and Infection. 2020 May 7. pmid:32387682 <ul class="reflinks" data-doi="10.1016/j.micinf.2020.04.011"><li><a href="https://doi.org/10.1016/j.micinf.2020.04.011" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32387682" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Characteristics+of+asymptomatic+patients+with+SARS-CoV-2+infection+in+Jinan%2C+China+Ma+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref32"><span class="order">32. </span><a name="pone.0249090.ref032" id="pone.0249090.ref032" class="link-target"></a>Meng H, Xiong R, He R, Lin W, Hao B, Zhang L, et al. CT imaging and clinical course of asymptomatic cases with COVID-19 pneumonia at admission in Wuhan, China. Journal of Infection. 2020 Apr 12. pmid:32294504 <ul class="reflinks" data-doi="10.1016/j.jinf.2020.04.004"><li><a href="https://doi.org/10.1016/j.jinf.2020.04.004" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32294504" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=CT+imaging+and+clinical+course+of+asymptomatic+cases+with+COVID-19+pneumonia+at+admission+in+Wuhan%2C+China+Meng+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref33"><span class="order">33. </span><a name="pone.0249090.ref033" id="pone.0249090.ref033" class="link-target"></a>Mizumoto K, Kagaya K, Zarebski A, Chowell G. Estimating the asymptomatic proportion of coronavirus disease 2019 (COVID-19) cases on board the Diamond Princess cruise ship, Yokohama, Japan, 2020. Eurosurveillance. 2020 Mar 12;25(10):2000180. <ul class="reflinks"><li><a href="#" data-author="Mizumoto" data-cit="MizumotoK%2C%20KagayaK%2C%20ZarebskiA%2C%20ChowellG.%20Estimating%20the%20asymptomatic%20proportion%20of%20coronavirus%20disease%202019%20%28COVID-19%29%20cases%20on%20board%20the%20Diamond%20Princess%20cruise%20ship%2C%20Yokohama%2C%20Japan%2C%202020.%20Eurosurveillance.%202020%20Mar%2012%3B25%2810%29%3A2000180." data-title="Estimating%20the%20asymptomatic%20proportion%20of%20coronavirus%20disease%202019%20%28COVID-19%29%20cases%20on%20board%20the%20Diamond%20Princess%20cruise%20ship%2C%20Yokohama%2C%20Japan%2C%202020" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Estimating+the+asymptomatic+proportion+of+coronavirus+disease+2019+%28COVID-19%29+cases+on+board+the+Diamond+Princess+cruise+ship%2C+Yokohama%2C+Japan%2C+2020+Mizumoto+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref34"><span class="order">34. </span><a name="pone.0249090.ref034" id="pone.0249090.ref034" class="link-target"></a>Nishiura H, Kobayashi T, Miyama T, Suzuki A, Jung SM, Hayashi K, et al. Estimation of the asymptomatic ratio of novel coronavirus infections (COVID-19). International journal of infectious diseases. 2020 M. pmid:33303095 <ul class="reflinks" data-doi="10.1016/j.jebdp.2020.101499"><li><a href="https://doi.org/10.1016/j.jebdp.2020.101499" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/33303095" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Estimation+of+the+asymptomatic+ratio+of+novel+coronavirus+infections+%28COVID-19%29+Nishiura+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref35"><span class="order">35. </span><a name="pone.0249090.ref035" id="pone.0249090.ref035" class="link-target"></a>Noh JY, Yoon JG, Seong H, Choi WS, Sohn JW, Cheong HJ, et al. Asymptomatic infection and atypical manifestations of COVID-19: comparison of viral shedding duration. The Journal of Infection. 2020 May 21. pmid:32445728 <ul class="reflinks" data-doi="10.1016/j.jinf.2020.05.035"><li><a href="https://doi.org/10.1016/j.jinf.2020.05.035" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32445728" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+infection+and+atypical+manifestations+of+COVID-19%3A+comparison+of+viral+shedding+duration+Noh+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref36"><span class="order">36. </span><a name="pone.0249090.ref036" id="pone.0249090.ref036" class="link-target"></a>Rivett L, Sridhar S, Sparkes D, Routledge M, Jones NK, Forrest S, et al. Screening of healthcare workers for SARS-CoV-2 highlights the role of asymptomatic carriage in COVID-19 transmission. Elife. 2020 M. pmid:32392129 <ul class="reflinks" data-doi="10.7554/eLife.58728"><li><a href="https://doi.org/10.7554/eLife.58728" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32392129" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Screening+of+healthcare+workers+for+SARS-CoV-2+highlights+the+role+of+asymptomatic+carriage+in+COVID-19+transmission+Rivett+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref37"><span class="order">37. </span><a name="pone.0249090.ref037" id="pone.0249090.ref037" class="link-target"></a>Tabata S, Imai K, Kawano S, Ikeda M, Kodama T, Miyoshi K, et al. Clinical characteristics of COVID-19 in 104 people with SARS-CoV-2 infection on the Diamond Princess cruise ship: a retrospective analysis. The La. pmid:32539988 <ul class="reflinks" data-doi="10.1016/S1473-3099(20)30482-5"><li><a href="https://doi.org/10.1016/S1473-3099(20)30482-5" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32539988" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Clinical+characteristics+of+COVID-19+in+104+people+with+SARS-CoV-2+infection+on+the+Diamond+Princess+cruise+ship%3A+a+retrospective+analysis+Tabata+" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref38"><span class="order">38. </span><a name="pone.0249090.ref038" id="pone.0249090.ref038" class="link-target"></a>Tian S, Hu N, Lou J, Chen K, Kang X, Xiang Z, et al. Characteristics of COVID-19 infection in Beijing. Journal of Infection. 2020 Feb 27. <ul class="reflinks"><li><a href="#" data-author="Tian" data-cit="TianS%2C%20HuN%2C%20LouJ%2C%20ChenK%2C%20KangX%2C%20XiangZ%2C%20et%20al.%20Characteristics%20of%20COVID-19%20infection%20in%20Beijing.%20Journal%20of%20Infection.%202020%20Feb%2027." data-title="Characteristics%20of%20COVID-19%20infection%20in%20Beijing" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Characteristics+of+COVID-19+infection+in+Beijing+Tian+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref39"><span class="order">39. </span><a name="pone.0249090.ref039" id="pone.0249090.ref039" class="link-target"></a>Wan R, Mao ZQ, He LY, Hu YC. Evidence from two cases of asymptomatic infection with SARS-CoV-2: Are 14 days of isolation sufficient?. International Journal of Infectious Diseases. 2020 Jun 1;95:174–5. pmid:32251796 <ul class="reflinks" data-doi="10.1016/j.ijid.2020.03.041"><li><a href="https://doi.org/10.1016/j.ijid.2020.03.041" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32251796" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Evidence+from+two+cases+of+asymptomatic+infection+with+SARS-CoV-2%3A+Are+14+days+of+isolation+sufficient%3F+Wan+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref40"><span class="order">40. </span><a name="pone.0249090.ref040" id="pone.0249090.ref040" class="link-target"></a>Wong J, Abdul Aziz AB, Chaw L, Mahamud A, Griffith MM, Ying-Ru LO, et al. High proportion of asymptomatic and presymptomatic COVID-19 infections in travelers and returning residents to Brunei. Journal of Travel Medicine. 2020 May 5. <ul class="reflinks"><li><a href="#" data-author="Wong" data-cit="WongJ%2C%20Abdul%20AzizAB%2C%20ChawL%2C%20MahamudA%2C%20GriffithMM%2C%20Ying-RuLO%2C%20et%20al.%20High%20proportion%20of%20asymptomatic%20and%20presymptomatic%20COVID-19%20infections%20in%20travelers%20and%20returning%20residents%20to%20Brunei.%20Journal%20of%20Travel%20Medicine.%202020%20May%205." data-title="High%20proportion%20of%20asymptomatic%20and%20presymptomatic%20COVID-19%20infections%20in%20travelers%20and%20returning%20residents%20to%20Brunei" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=High+proportion+of+asymptomatic+and+presymptomatic+COVID-19+infections+in+travelers+and+returning+residents+to+Brunei+Wong+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref41"><span class="order">41. </span><a name="pone.0249090.ref041" id="pone.0249090.ref041" class="link-target"></a>Xu T, Huang R, Zhu L, Wang J, Cheng J, Zhang B, et al. Epidemiological and clinical features of asymptomatic patients with SARS‐CoV‐2 infection. Journal of medical virology. 2020 Apr 28. <ul class="reflinks"><li><a href="#" data-author="Xu" data-cit="XuT%2C%20HuangR%2C%20ZhuL%2C%20WangJ%2C%20ChengJ%2C%20ZhangB%2C%20et%20al.%20Epidemiological%20and%20clinical%20features%20of%20asymptomatic%20patients%20with%20SARS%E2%80%90CoV%E2%80%902%20infection.%20Journal%20of%20medical%20virology.%202020%20Apr%2028." data-title="Epidemiological%20and%20clinical%20features%20of%20asymptomatic%20patients%20with%20SARS%E2%80%90CoV%E2%80%902%20infection" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Epidemiological+and+clinical+features+of+asymptomatic+patients+with+SARS%E2%80%90CoV%E2%80%902+infection+Xu+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref42"><span class="order">42. </span><a name="pone.0249090.ref042" id="pone.0249090.ref042" class="link-target"></a>Zhao D, Wang M, Wang M, Zhao Y, Zheng Z, Li X, et al. Asymptomatic infection by SARS-CoV-2 in healthcare workers: a study in a large teaching hospital in Wuhan, China. International Journal of Infectious Diseases. 2020 Aug 3. <ul class="reflinks"><li><a href="#" data-author="Zhao" data-cit="ZhaoD%2C%20WangM%2C%20WangM%2C%20ZhaoY%2C%20ZhengZ%2C%20LiX%2C%20et%20al.%20Asymptomatic%20infection%20by%20SARS-CoV-2%20in%20healthcare%20workers%3A%20a%20study%20in%20a%20large%20teaching%20hospital%20in%20Wuhan%2C%20China.%20International%20Journal%20of%20Infectious%20Diseases.%202020%20Aug%203." data-title="Asymptomatic%20infection%20by%20SARS-CoV-2%20in%20healthcare%20workers%3A%20a%20study%20in%20a%20large%20teaching%20hospital%20in%20Wuhan" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+infection+by+SARS-CoV-2+in+healthcare+workers%3A+a+study+in+a+large+teaching+hospital+in+Wuhan+Zhao+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref43"><span class="order">43. </span><a name="pone.0249090.ref043" id="pone.0249090.ref043" class="link-target"></a>Zhou X, Li Y, Li T, Zhang W. Follow-up of asymptomatic patients with SARS-CoV-2 infection. Clinical Microbiology and Infection. 2020 Mar 28. <ul class="reflinks"><li><a href="#" data-author="Zhou" data-cit="ZhouX%2C%20LiY%2C%20LiT%2C%20ZhangW.%20Follow-up%20of%20asymptomatic%20patients%20with%20SARS-CoV-2%20infection.%20Clinical%20Microbiology%20and%20Infection.%202020%20Mar%2028." data-title="Follow-up%20of%20asymptomatic%20patients%20with%20SARS-CoV-2%20infection" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Follow-up+of+asymptomatic+patients+with+SARS-CoV-2+infection+Zhou+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref44"><span class="order">44. </span><a name="pone.0249090.ref044" id="pone.0249090.ref044" class="link-target"></a>Zhou R, Li F, Chen F, Liu H, Zheng J, Lei C, et al. Viral dynamics in asymptomatic patients with COVID-19. Int J Infect Dis. 2020 May 11;96:288–90. pmid:32437933 <ul class="reflinks" data-doi="10.1016/j.ijid.2020.05.030"><li><a href="https://doi.org/10.1016/j.ijid.2020.05.030" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32437933" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Viral+dynamics+in+asymptomatic+patients+with+COVID-19+Zhou+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref45"><span class="order">45. </span><a name="pone.0249090.ref045" id="pone.0249090.ref045" class="link-target"></a>Peeri NC, Shrestha N, Rahman MS, Zaki R, Tan Z, Bibi S, et al. The SARS, MERS and novel coronavirus (COVID-19) epidemics, the newest and biggest global health threats: what lessons have we learned?. Internationa. pmid:32086938 <ul class="reflinks" data-doi="10.1093/ije/dyaa033"><li><a href="https://doi.org/10.1093/ije/dyaa033" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/32086938" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=The+SARS%2C+MERS+and+novel+coronavirus+%28COVID-19%29+epidemics%2C+the+newest+and+biggest+global+health+threats%3A+what+lessons+have+we+learned%3F+Peeri+" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref46"><span class="order">46. </span><a name="pone.0249090.ref046" id="pone.0249090.ref046" class="link-target"></a>Borras-Bermejo B, Martínez-Gómez X, San Miguel MG, Esperalba J, Antón A, Martin E, et al. Asymptomatic SARS-CoV-2 Infection in Nursing Homes, Barcelona, Spain, April 2020. Emerging Infectious Diseases. 2020 Ju. <ul class="reflinks"><li><a href="#" data-author="Borras-Bermejo" data-cit="Borras-BermejoB%2C%20Mart%C3%ADnez-G%C3%B3mezX%2C%20San%20MiguelMG%2C%20EsperalbaJ%2C%20Ant%C3%B3nA%2C%20MartinE%2C%20et%20al.%20Asymptomatic%20SARS-CoV-2%20Infection%20in%20Nursing%20Homes%2C%20Barcelona%2C%20Spain%2C%20April%202020.%20Emerging%20Infectious%20Diseases.%202020%20Ju." data-title="Asymptomatic%20SARS-CoV-2%20Infection%20in%20Nursing%20Homes%2C%20Barcelona%2C%20Spain%2C%20April%202020" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+SARS-CoV-2+Infection+in+Nursing+Homes%2C+Barcelona%2C+Spain%2C+April+2020+Borras-Bermejo+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref47"><span class="order">47. </span><a name="pone.0249090.ref047" id="pone.0249090.ref047" class="link-target"></a>Al-Tawfiq JA, Gautret P. Asymptomatic Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection: extent and implications for infection control: a systematic review. Travel medicine and infectious disease. 2019 Jan 1;27:27–32. pmid:30550839 <ul class="reflinks" data-doi="10.1016/j.tmaid.2018.12.003"><li><a href="https://doi.org/10.1016/j.tmaid.2018.12.003" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/30550839" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Asymptomatic+Middle+East+Respiratory+Syndrome+Coronavirus+%28MERS-CoV%29+infection%3A+extent+and+implications+for+infection+control%3A+a+systematic+review+Al-Tawfiq+2019" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref48"><span class="order">48. </span><a name="pone.0249090.ref048" id="pone.0249090.ref048" class="link-target"></a>Fraser C, Riley S, Anderson RM, Ferguson NM. Factors that make an infectious disease outbreak controllable. Proceedings of the National Academy of Sciences. 2004 Apr 20;101(16):6146–51. pmid:15071187 <ul class="reflinks" data-doi="10.1073/pnas.0307506101"><li><a href="https://doi.org/10.1073/pnas.0307506101" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/15071187" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Factors+that+make+an+infectious+disease+outbreak+controllable+Fraser+2004" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref49"><span class="order">49. </span><a name="pone.0249090.ref049" id="pone.0249090.ref049" class="link-target"></a>Chan PK, Ip M, Ng KC, Chan RC, Wu A, Lee N, et al. Severe acute respiratory syndrome–associated coronavirus infection. Emerging infectious diseases. 2003 Nov;9(11):1453. pmid:14718090 <ul class="reflinks" data-doi="10.3201/eid0911.030421"><li><a href="https://doi.org/10.3201/eid0911.030421" data-author="doi-provided" data-cit="doi-provided" data-title="doi-provided" target="_new" title="Go to article"> View Article </a></li><li><a href="http://www.ncbi.nlm.nih.gov/pubmed/14718090" target="_new" title="Go to article in PubMed"> PubMed/NCBI </a></li><li><a href="http://scholar.google.com/scholar?q=Severe+acute+respiratory+syndrome%E2%80%93associated+coronavirus+infection+Chan+2003" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li><li id="ref50"><span class="order">50. </span><a name="pone.0249090.ref050" id="pone.0249090.ref050" class="link-target"></a>Petrosillo N, Viceconte G, Ergonul O, Ippolito G, Petersen E. COVID-19, SARS and MERS: are they closely related?. Clinical Microbiology and Infection. 2020 Mar 28. <ul class="reflinks"><li><a href="#" data-author="Petrosillo" data-cit="PetrosilloN%2C%20ViceconteG%2C%20ErgonulO%2C%20IppolitoG%2C%20PetersenE.%20COVID-19%2C%20SARS%20and%20MERS%3A%20are%20they%20closely%20related%3F.%20Clinical%20Microbiology%20and%20Infection.%202020%20Mar%2028." data-title="COVID-19%2C%20SARS%20and%20MERS%3A%20are%20they%20closely%20related%3F" target="_new" title="Go to article in CrossRef"> View Article </a></li><li><a href="http://scholar.google.com/scholar?q=COVID-19%2C+SARS+and+MERS%3A+are+they+closely+related%3F+Petrosillo+2020" target="_new" title="Go to article in Google Scholar"> Google Scholar </a></li></ul></li></ol></div> <div class="ref-tooltip"> <div class="ref_tooltip-content"> </div> </div> </div> </div> </div> </section> <aside class="article-aside">  <div class="dload-menu"> <div class="dload-pdf"> <a href="/plosone/article/file?id=10.1371/journal.pone.0249090&type=printable" id="downloadPdf" target="_blank">Download PDF</a> </div> <div data-js-tooltip-hover="trigger" class="dload-hover">  <ul class="dload-xml" data-js-tooltip-hover="target"> <li><a href="/plosone/article/citation?id=10.1371/journal.pone.0249090" id="downloadCitation">Citation</a></li> <li><a href="/plosone/article/file?id=10.1371/journal.pone.0249090&type=manuscript" id="downloadXml">XML</a> </li> </ul> </div> </div> <div class="aside-container"> <div class="print-article" id="printArticle" data-js-tooltip-hover="trigger"> <a href="#" onclick="window.print(); 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