This evidence review was compiled by members of the CITF Secretariat with the input from experts affiliated with the CITF and does not necessarily reflect the views of all CITF members.

By Marija Djekic-Ivankovic

The proportion of people in the U.S. with SARS-CoV-2 antibodies remains uncertain. A new study published in JAMA used a sample of 1.44 million blood samples from July 2020 through May 2021 to estimate the SARS-CoV-2 seroprevalence in the general US population aged 16 years and older. Findings indicate that the estimated SARS-CoV-2 seroprevalence increased over time and varied by age, race, and ethnicity, as well as by geographic region.

Key findings:

  • The estimated SARS-CoV-2 seroprevalence (weighted for differences between the study sample and the general population) increased from 3.5% in July 2020 to 20.2% for infection-induced antibodies in May 2021.
  • The combined infection- and vaccination-induced seroprevalence estimate in May 2021 was 83.3%.
  • 17 blood collection organizations with blood donations from all 50 US states, as well as Washington DC and Puerto Rico, were organized into 66 study-specific regions, representing a catchment of 74% of the US population. However, compared with the general population residing within the study regions, significantly more blood donors in the study were non-Hispanic White (85.0% vs 61.2%) and aged 50 to 64 years, indicating that the sample may not necessarily be representative of the general population.

Jones J, Stone M, Sulaeman H, Fink R, Dave H, Levy M, Di Germanio C, Green V, Notari E, Saa P, Biggerstaff B, Strauss D, Kessler D, Vassallo R, Reik R, Rossmann S, Destree M, Nguyen KA, Sayers M, Lough C, Bougie D, Ritter M, Latoni G, Weales B, Sime S, Gorlin J, Brown N, Gould C, Berney K, Benoit T, Miller M, Freeman D, Kartik D, Fry A, Azziz-Baumgartner E, Hall A, MacNeil A, Gundlapalli A, Basavaraju S, Gerber S, Patton M, Custer B, Williamson P, Simmons G, Thornburg N, Kleinman S, Stramer S, Opsomer J and Busch M. Estimated US Infection- and Vaccine-Induced SARS-CoV-2 Seroprevalence Based on Blood Donations, July 2020-May 2021. JAMA, doi: 10.1001/jama.2021.15161