Prevalence of Asymptomatic SARS-CoV-2 Infection
Authors: Dongsheng Han, Jinming Li
Journal: Annals of Internal Medicine (2021)

LettersFebruary 2021Prevalence of Asymptomatic SARS-CoV-2 InfectionFREEDongsheng Han, PhD, Jinming Li, PhDDongsheng Han, PhDNational Center for Clinical Laboratories, Beijing Hospital, and National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, ChinaSearch for more papers by this author, Jinming Li, PhDNational Center for Clinical Laboratories, Beijing Hospital, and National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, ChinaSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/L20-1281 SectionsAboutVisual AbstractPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:The existence of a substantial but unclear number of asymptomatic patients with SARS-CoV-2 worldwide has raised concerns among global public health authorities. Oran and Topol's narrative review (1) concluded that asymptomatic patients might account for approximately 40% to 45% of SARS-CoV-2 infections on the basis of results from 16 cohort studies from different sources. Unfortunately, their review did not include any studies from China.In China, the detection of asymptomatic infection is a core task for combating the spread of COVID-19. Studies in China that have been peer-reviewed and officially published show that asymptomatic infection occurred in no more than 20% of cases (specifically, between 6% and 15.8%). This proportion is much lower than the 40% to 45% reported in Oran and Topol's review.These studies in China were based on different populations, including hospitalized contacts of patients with COVID-19 (34 of 279 [12.2%] persons in Wuhan City in Hubei province [2]), all infected persons tracked throughout a city (25 of 391 [6%] persons in Shenzhen City in Guangdong province [3]), and asymptomatic infections in childhood cases across China (94 of 731 [12.9%] persons [4]) and in Wuhan city (27 of 171 [15.8%] persons [5]). Because of the differences in the study setting and included populations of all the studies (including the 16 cohorts in Oran and Topol's narrative review), the inferred proportion of asymptomatic SARS-CoV-2 infection—whether 20% or 40%—may not be accurate. The true proportion needs to be determined by more carefully designed studies in the future. Nevertheless, in the context of the current research, we believe that Oran and Topol's review should supplement the information we provide here in order to give readers a more objective understanding of the proportion of asymptomatic infections.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. Wang Y, He Y, Tong J, et al. Characterization of an asymptomatic cohort of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected individuals outside of Wuhan, China. Clin Infect Dis. 2020;71:2132-8. [PMID: 32442265] doi:10.1093/cid/ciaa629 CrossrefMedlineGoogle Scholar3. Bi Q, Wu Y, Mei S, et al. Epidemiology and transmission of COVID-19 in 391 cases and 1286 of their close contacts in Shenzhen, China: a retrospective cohort study. Lancet Infect Dis. 2020;20:911-9. [PMID: 32353347] doi:10.1016/S1473-3099(20)30287-5 CrossrefMedlineGoogle Scholar4. Dong Y, Mo X, Hu Y, et al. Epidemiology of COVID-19 among children in China. Pediatrics. 2020;145. [PMID: 32179660] doi:10.1542/peds.2020-0702 CrossrefMedlineGoogle Scholar5. Lu X, Zhang L, Du H, et al; Chinese Pediatric Novel Coronavirus Study Team. SARS-CoV-2 infection in children [Letter]. N Engl J Med. 2020;382:1663-5. [PMID: 32187458] doi:10.1056/NEJMc2005073 CrossrefMedlineGoogle Scholar Comments 0 Comments Sign In to Submit A Comment Author, Article, and Disclosure InformationAuthors: Dongsheng Han, PhD; Jinming Li, PhDAffiliations: National Center for Clinical Laboratories, Beijing Hospital, and National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, ChinaDisclosures: Authors have disclosed no conflicts of interest. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=L20-1281. 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