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. 2021 Apr 1;181(4):450-460.
doi: 10.1001/jamainternmed.2020.7976.

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

Kristina L Bajema  1 , Ryan E Wiegand  1 , Kendra Cuffe  1 , Sadhna V Patel  1 , Ronaldo Iachan  2 , Travis Lim  1 , Adam Lee  2 , Davia Moyse  2 , Fiona P Havers  1 , Lee Harding  2 , Alicia M Fry  1 , Aron J Hall  1 , Kelly Martin  2 , Marjorie Biel  2 , Yangyang Deng  2 , William A Meyer 3rd  3 , Mohit Mathur  4 , Tonja Kyle  2 , Adi V Gundlapalli  1 , Natalie J Thornburg  1 , Lyle R Petersen  1 , Chris Edens  1
Affiliations

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

Kristina L Bajema et al. JAMA Intern Med. .

Abstract

Importance: 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.

Objective: 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.

Design, setting, and participants: 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.

Exposures: Infection with SARS-CoV-2.

Main outcomes and measures: 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.

Results: 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.

Conclusions and relevance: 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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Conflict of interest statement

Conflict of Interest Disclosures: ICF, Inc, Quest Diagnostics, and BioReference Laboratories were awarded federal contracts from CDC for the execution of this project. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. SARS-CoV-2 Prevalence Estimates by US Jurisdiction During Testing Periods From July 27 to August 13, August 10 to 27, August 24 to September 10, and September 7 to 24, 2020
Estimates are shown with 95% bootstrap CIs. Estimates could not be calculated for Hawaii, North Dakota, South Dakota, and Wyoming during select periods during which there were fewer than 75 samples.
Figure 2.
Figure 2.. Sex-Stratified SARS-CoV-2 Prevalence Estimates by Jurisdiction During Testing Periods 1 to 4
Estimates could not be calculated for select jurisdictions where there were fewer than 75 samples or no samples were provided for a given reporting subgroup.
Figure 3.
Figure 3.. Age-Stratified SARS-CoV-2 Prevalence Estimates by Jurisdiction During Testing Periods 1 to 4
Estimates could not be calculated for select jurisdictions where there were fewer than 75 samples or no samples were provided for a given reporting subgroup.
Figure 4.
Figure 4.. Metropolitan Status–Stratified SARS-CoV-2 Prevalence Estimates by Jurisdiction During Testing Periods 1 to 4
Estimates could not be calculated for select jurisdictions where there were fewer than 75 samples or no samples were provided for a given reporting subgroup. The asterisks indicate that Delaware, New Jersey, Rhode Island, and Washington DC do not contain nonmetropolitan counties.
See this image and copyright information in PMC

Comment in

References

    1. Holshue ML, DeBolt C, Lindquist S, et al. ; Washington State 2019-nCoV Case Investigation Team . First case of 2019 novel coronavirus in the United States. N Engl J Med. 2020;382(10):929-936. doi:10.1056/NEJMoa2001191 - DOI - PMC - PubMed
    1. California Department of Public Health . CDC confirms possible first instance of COVID-19 community transmission in California. Accessed June 17, 2020. https://www.cdph.ca.gov/Programs/OPA/Pages/NR20-006.aspx
    1. Jorden MA, Rudman SL, Villarino E, et al. ; CDC COVID-19 Response Team . Evidence for limited early spread of COVID-19 within the United States, January-February 2020. MMWR Morb Mortal Wkly Rep. 2020;69(22):680-684. doi:10.15585/mmwr.mm6922e1 - DOI - PMC - PubMed
    1. Washington State Department of Health . Additional cases of COVID-19 in Washington state. Accessed June 17, 2020. https://www.doh.wa.gov/Newsroom/Articles/ID/1103/Additional-Cases-of-COV...
    1. Spellberg B, Haddix M, Lee R, et al. . Community prevalence of SARS-CoV-2 among patients with influenzalike illnesses presenting to a Los Angeles medical center in March 2020. JAMA. 2020;323(19):1966-1967. doi:10.1001/jama.2020.4958 - DOI - PMC - PubMed