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Estimated SARS-CoV-2 Seroprevalence in the US as of September 2020.

  • Bajema, Kristina L1
  • Wiegand, Ryan E1
  • Cuffe, Kendra1
  • Patel, Sadhna V1
  • Iachan, Ronaldo2
  • Lim, Travis1
  • Lee, Adam2
  • Moyse, Davia2
  • Havers, Fiona P1
  • Harding, Lee2
  • Fry, Alicia M1
  • Hall, Aron J1
  • Martin, Kelly2
  • Biel, Marjorie2
  • Deng, Yangyang2
  • Meyer, William A 3rd3
  • Mathur, Mohit4
  • Kyle, Tonja2
  • Gundlapalli, Adi V1
  • Thornburg, Natalie J1
  • And 2 more
  • 1 COVID-19 Response, US Centers for Disease Control and Prevention, Atlanta, Georgia. , (Georgia)
  • 2 ICF Inc, Fairfax, Virginia.
  • 3 Quest Diagnostics, Secaucus, New Jersey. , (Jersey)
  • 4 BioReference Laboratories, Elmwood Park, New Jersey. , (Jersey)
Published Article
JAMA internal medicine
Publication Date
Apr 01, 2021
DOI: 10.1001/jamainternmed.2020.7976
PMID: 33231628


Case-based surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection likely underestimates the true prevalence of infections. Large-scale seroprevalence surveys can better estimate infection across many geographic regions. To estimate the prevalence of persons with SARS-CoV-2 antibodies using residual sera from commercial laboratories across the US and assess changes over time. This repeated, cross-sectional study conducted across all 50 states, the District of Columbia, and Puerto Rico used a convenience sample of residual serum specimens provided by persons of all ages that were originally submitted for routine screening or clinical management from 2 private clinical commercial laboratories. Samples were obtained during 4 collection periods: July 27 to August 13, August 10 to August 27, August 24 to September 10, and September 7 to September 24, 2020. Infection with SARS-CoV-2. The proportion of persons previously infected with SARS-CoV-2 as measured by the presence of antibodies to SARS-CoV-2 by 1 of 3 chemiluminescent immunoassays. Iterative poststratification was used to adjust seroprevalence estimates to the demographic profile and urbanicity of each jurisdiction. Seroprevalence was estimated by jurisdiction, sex, age group (0-17, 18-49, 50-64, and ≥65 years), and metropolitan/nonmetropolitan status. Of 177 919 serum samples tested, 103 771 (58.3%) were from women, 26 716 (15.0%) from persons 17 years or younger, 47 513 (26.7%) from persons 65 years or older, and 26 290 (14.8%) from individuals living in nonmetropolitan areas. Jurisdiction-level seroprevalence over 4 collection periods ranged from less than 1% to 23%. In 42 of 49 jurisdictions with sufficient samples to estimate seroprevalence across all periods, fewer than 10% of people had detectable SARS-CoV-2 antibodies. Seroprevalence estimates varied between sexes, across age groups, and between metropolitan/nonmetropolitan areas. Changes from period 1 to 4 were less than 7 percentage points in all jurisdictions and varied across sites. This cross-sectional study found that as of September 2020, most persons in the US did not have serologic evidence of previous SARS-CoV-2 infection, although prevalence varied widely by jurisdiction. Biweekly nationwide testing of commercial clinical laboratory sera can play an important role in helping track the spread of SARS-CoV-2 in the US.

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