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SARS-CoV-2 Cumulative Incidence, United States, August-December 2020
25 Pages Posted: 29 Apr 2021
More...Abstract
Background: Reported COVID-19 cases underestimate SARS-CoV-2 infections. We conducted a national probability survey of US households to estimate the cumulative incidence of infection adjusted for antibody waning.
Methods: From August to December 2020, a multistage random sample of US addresses were mailed a survey and materials to self-collect nasal swabs and dried blood spots. One adult household member was randomly selected to complete the survey and mail specimens for virus and antibody testing. We estimated cumulative incidence of SARS-CoV-2 infections adjusted for waning antibodies and calculated reported fraction and infection fatality ratio (IFR). Differences in seropositivity among demographic, geographic and clinical subgroups were explored with weighted prevalence ratios (PR).
Results: Among 39,500 sampled households, 4,654 respondents provided surveys and valid specimens. Cumulative incidence adjusted for waning was 11.9% (95% credible interval (CrI): 10.5-13.5%) as of October 30, 2020. We estimated 30,332,842 (95% CrI: 26,703,753-34,335,338) total infections in the U.S. adult population by October 30, 2020.The reported fraction was 17% and the IFR was 0.85% among adults. Non-Hispanic Black (PR: 2.2) and Hispanic (PR: 3.1) persons were significantly more likely than White non-Hispanic to be seropositive, as were those living in metropolitan areas (PR: 2.5).
Conclusions: One in 8 US adults had been infected with SARS-CoV-2, but few had been accounted for in public health reporting. Our data document that the scope of the COVID-19 pandemic is likely substantially underestimated by reported cases. Disparities in COVID-19 by race observed among reported cases cannot be attributed to differential diagnosis or reporting of infections in some population subgroups.
Funding Statement: This project was funded by the National Institute of Allergy and
Infectious Diseases, grant number 3R01AI143875-02S1, This project was partially funded by The Epidemiology and Laboratory Capacity for Infectious Diseases, Grant Number 6 NU50CK000539. This project was partially funded by the Woodruff Foundation.
Declaration of Interests: The authors declare no conflict of interest.
Ethics Approval Statement: The COVIDVu study was approved by the Emory University Institutional Review Board (STUDY00000695).
Suggested Citation: Suggested Citation