Prevalence of Asymptomatic SARS-CoV-2 Infection
Authors: Daniel T. Halperin
Journal: Annals of Internal Medicine (2021)

LettersFebruary 2021Prevalence of Asymptomatic SARS-CoV-2 InfectionFREEDaniel T. Halperin, PhDDaniel T. Halperin, PhDGillings School of Global Public Health, University of North Carolina, Chapel Hill, North CarolinaSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/L20-1282 SectionsAboutVisual AbstractPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:Oran and Topol's narrative review (1) is commendably useful for being one of the first attempts to estimate the proportion of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) carriers who are asymptomatic. However, their conclusion that therefore “asymptomatic SARS-CoV-2 infection . . . is a significant factor in the rapid progression of [coronavirus disease 2019 (COVID-19)]” seems to be utterly unsubstantiated. This is surprising considering Annals' normally rigorous peer-review standards.Oran and Topol's assertion in the abstract that “asymptomatic persons . . . can transmit the virus” is supported by only 2 data. They claim that the authors of an Italian study “confirmed that several new cases of SARS-CoV-2 infection . . . had been caused by exposure to asymptomatic persons.” However, the cited (non–peer-reviewed) article merely mentions that 2 or at most 3 of 8 persons studied “may [emphasis added] have become infected from an asymptomatic carrier” (2). For example, the authors of this study state, “Subject 5 reported meeting an asymptomatic infected individual before the lockdown.” Of note, the same study reported, “No infections were detected in . . . 234 tested children [younger than 11 years], despite . . . living in [the] same household as infected people.” This finding is consistent with other evidence that children are much less likely to become infected and, when infected, are typically asymptomatic (as opposed to presymptomatic) carriers (3, 4).The only other evidence cited by Oran and Topol to support the role of asymptomatic transmission comes from just 1 of the other 16 cohort studies they reviewed. They include the following statement from that study: “More than half of [infected nursing facility] residents . . . were asymptomatic at the time of testing and most likely contributed to transmission” (5). In fact, the cited study explains that “7 days after their positive test, 24 of 27 asymptomatic residents (89%) had onset of symptoms and were recategorized as pre-symptomatic.” Oran and Topol seem to have confused the same issue of asymptomatic versus presymptomatic transmission that they attempt to clarify at the beginning of their own review when they state, “To be clear, the asymptomatic individual . . . will never develop symptoms.”I ask that the Editors retract this review or at least request that the authors modify their perhaps unintentional but clearly misleading conclusion about the contagiousness of asymptomatic SARS-CoV-2 carriers. Any objective expert or careful reader surely would wonder whether the review's conclusion, which warns about “the high risk for silent spread by asymptomatic persons” and suggests that therefore “[m]edical practice and public health measures should be modified to address this challenge,” is in fact substantiated by the “data” cited by the authors (that is, that 2 or 3 persons in Italy who reported having had contact with asymptomatic carriers may thus have become infected). This review and in particular its dubiously substantiated conclusion have been widely cited—including in many reports asserting that “up to 45% of all Covid-19 infections are from asymptomatic persons” (4)—and therefore urgently require correction.References1. Oran DP, Topol EJ. Prevalence of asymptomatic SARS-CoV-2 infection. A narrative review. Ann Intern Med. 2020;173:362-7. doi:10.7326/M20-3012 LinkGoogle Scholar2. Lavezzo E, Franchin E, Ciavarella C, et al. Suppression of COVID-19 outbreak in the municipality of Vo’, Italy. medRxiv. Preprint posted online 18 April 2020. doi:10.1101/2020.04.17.20053157 Google Scholar3. Halperin DT. Coping with COVID-19: learning from past pandemics to avoid pitfalls and panic. Global Health Sci Pract. 2020;8:155-65. doi:10.9745/GHSP-D-20-00189 Google Scholar4. Halperin DT. Facing COVID Without Panic: 12 Common Myths and 12 Lesser Known Facts about the Pandemic, Clearly Explained by an Epidemiologist. Amazon; 2020. Google Scholar5. Arons MM, Hatfield KM, Reddy SC, et al; Public Health–Seattle and King County and CDC COVID-19 Investigation Team. Presymptomatic SARS-CoV-2 infections and transmission in a skilled nursing facility. N Engl J Med. 2020;382:2081-90. [PMID: 32329971] doi:10.1056/NEJMoa2008457 CrossrefMedlineGoogle Scholar Comments 0 Comments Sign In to Submit A Comment Author, Article, and Disclosure InformationAuthors: Daniel T. Halperin, PhDAffiliations: Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North CarolinaDisclosures: The author has disclosed no conflicts of interest. The form can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=L20-1282. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetailsSee AlsoPrevalence of Asymptomatic SARS-CoV-2 Infection Daniel P. Oran and Eric J. Topol Prevalence of Asymptomatic SARS-CoV-2 Infection Muge Cevik , Isaac I. Bogoch , Gail Carson , Eric D’Ortenzio , Krutika Kuppalli Prevalence of Asymptomatic SARS-CoV-2 Infection Andrew N. Cohen , Bruce Kessel Prevalence of Asymptomatic SARS-CoV-2 Infection Daniel P. Oran , Eric J. Topol Prevalence of Asymptomatic SARS-CoV-2 Infection N. Belgin Akilli , Ramazan Koylu Prevalence of Asymptomatic SARS-CoV-2 Infection Dongsheng Han , Jinming Li Prevalence of Asymptomatic SARS-CoV-2 Infection Charles Elder Metrics Cited byEffects of physical activity on the severity of illness and mortality in COVID-19 patients: A systematic review and meta-analysisCharacterization of Specific Humoral Immunity in Asymptomatic SARS-CoV-2 InfectionViral Dynamics and Real-Time RT-PCR Ct Values Correlation with Disease Severity in COVID-19 February 2021Volume 174, Issue 2 Page: 283 Keywords Children Cohort studies Conflicts of interest COVID-19 Disclosure Pediatric infections Prevention, policy, and public health Risk management ePublished: 16 February 2021 Issue Published: February 2021 Copyright & PermissionsCopyright © 2021 by American College of Physicians. All Rights Reserved.PDF downloadLoading ...