Estimated SARS-CoV-2 Seroprevalence in the US as of September 2020 | Global Health | JN Learning | AMA Ed Hub [Skip to Content]
[Skip to Content Landing]
Key Points

Question  What proportion of persons across 52 US jurisdictions had detectable antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from July to September 2020?

Findings  In this repeated, cross-sectional study of 177 919 residual clinical specimens, the estimated percentage of persons in a jurisdiction with detectable SARS-CoV-2 antibodies ranged from fewer than 1% to 23%. Over 4 sampling periods in 42 of 49 jurisdictions with calculated estimates, fewer than 10% of people had detectable SARS-CoV-2 antibodies.

Meaning  While SARS-CoV-2 antibody prevalence estimates varied widely across jurisdictions, most people in the US did not have evidence of previous SARS-CoV-2 infection.


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.

Sign in to take quiz and track your certificates

Buy This Activity

JN Learning™ is the home for CME and MOC from the JAMA Network. Search by specialty or US state and earn AMA PRA Category 1 CME Credit™ from articles, audio, Clinical Challenges and more. Learn more about CME/MOC

CME Disclosure Statement: Unless noted, all individuals in control of content reported no relevant financial relationships. If applicable, all relevant financial relationships have been mitigated.

Article Information

Accepted for Publication: November 6, 2020.

Published Online: November 24, 2020. doi:10.1001/jamainternmed.2020.7976

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Bajema KL et al. JAMA Internal Medicine.

Corresponding Author: Kristina L. Bajema, MD, MSc, US Centers for Disease Control and Prevention (CDC), 1600 Clifton Rd NE, Mailstop H24-6, Atlanta, GA 30329 (

Author Contributions: Drs Bajema and Edens had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Bajema, Iachan, Havers, Harding, Fry, Hall, Gundlapalli, Thornburg, Petersen, Edens.

Acquisition, analysis, or interpretation of data: Bajema, Wiegand, Cuffe, Patel, Iachan, Lim, Lee, Moyse, Harding, Kelly, Biel, Deng, Meyer, Mathur, Kyle, Gundlapalli, Thornburg, Petersen, Edens.

Drafting of the manuscript: Bajema, Wiegand, Cuffe, Patel, Iachan, Harding, Edens.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Bajema, Wiegand, Iachan, Lim, Lee, Harding, Kelly, Biel, Deng, Edens.

Obtained funding: Bajema, Cuffe, Havers, Fry, Hall, Gundlapalli, Petersen, Edens.

Administrative, technical, or material support: Bajema, Wiegand, Cuffe, Patel, Moyse, Havers, Fry, Hall, Meyer, Mathur, Kyle, Gundlapalli, Thornburg, Petersen, Edens.

Supervision: Iachan, Havers, Fry, Hall, Mathur, Meyer, Thornburg, Edens.

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.

Funding/Support: This work was supported by CDC (Atlanta, Georgia).

Role of the Funder/Sponsor: CDC had a role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The findings and conclusions in the article are those of the authors and do not necessarily represent the official position of CDC.

Additional Contributions: We thank Gabriele Richardson, PhD, CDC, for mapping support as well as other members of CDC for administrative and technical support: Teresa Kinley, MS, Melissa Carter, PhD, Lauren Peel, JD, Adrean Mabry, BS, Saraine Ross, BA, Jasmine Chaitram, MPH, Alex Hoffmaster, PhD, Subbian Panayampalli, PhD, William Duck, MS, Eduardo Azziz-Baumgartner, MD, Adam MacNeil, PhD. We thank Quest and BioReference for testing specimens. From Quest: Brian Jaffa, MS, Caterina Powell, BS, Rebecca Parsons, BS, Brian Young, AA, Carol Bledsoe, Nicki Sylvester, MBA, Bonnie Bouck, AA, Georgia Schoemaker, BS, Stephanie Buchler, Larry Hirsch, BS, Narshimlu Ramdas, BTech, Neelima Donur, MS, Jeff Crawford, BS. From BioReference: James Weisberger, MD, Dan McNichol, MBA, Ada Gazzillo, BS, Nick Cetani, MS, Cesar Abril, MBA, Angela Canada, BS, Amal Abadeer, BA, and Pamela Depuy. These individuals were not compensated directly by CDC for their participation in this specific study.

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/NEJMoa2001191PubMedGoogle ScholarCrossref
California Department of Public Health. CDC confirms possible first instance of COVID-19 community transmission in California. Accessed June 17, 2020.
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.mm6922e1PubMedGoogle ScholarCrossref
Washington State Department of Health. Additional cases of COVID-19 in Washington state. Accessed June 17, 2020.
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.2020.4958PubMedGoogle ScholarCrossref
Centers for Disease Control and Prevention. CDC COVID data tracker. Accessed November 2, 2020.
Sakurai  A , Sasaki  T , Kato  S ,  et al.  Natural history of asymptomatic SARS-CoV-2 infection.   N Engl J Med. 2020;383(9):885-886. doi:10.1056/NEJMc2013020PubMedGoogle ScholarCrossref
Payne  DC , Smith-Jeffcoat  SE , Nowak  G ,  et al; CDC COVID-19 Surge Laboratory Group.  SARS-CoV-2 infections and serologic responses from a sample of U.S. Navy service members—USS Theodore Roosevelt, April 2020.   MMWR Morb Mortal Wkly Rep. 2020;69(23):714-721. doi:10.15585/mmwr.mm6923e4PubMedGoogle ScholarCrossref
Yousaf  AR , Duca  LM , Chu  V ,  et al.  A prospective cohort study in non-hospitalized household contacts with SARS-CoV-2 infection: symptom profiles and symptom change over time.   Clin Infect Dis. 2020;ciaa1072. doi:10.1093/cid/ciaa1072PubMedGoogle Scholar
Havers  FP , Reed  C , Lim  T ,  et al.  Seroprevalence of Antibodies to SARS-CoV-2 in 10 Sites in the United States, March 23-May 12, 2020.   JAMA Intern Med. Published online July 21, 2020. doi:10.1001/jamainternmed.2020.4130.Google Scholar
Bendavid  E , Mulaney  B , Sood  N ,  et al  COVID-19 antibody seroprevalence in Santa Clara County, California.   medRxiv 2020; Accessed June 17, 2020.Google Scholar
Sood  N , Simon  P , Ebner  P ,  et al.  Seroprevalence of SARS-CoV-2-specific antibodies among adults in Los Angeles County, California, on April 10-11 2020.   JAMA. Published online May 18, 2020. doi:10.1001/jama.2020.8279Google Scholar
Self  WH , Tenforde  MW , Stubblefield  WB ,  et al; CDC COVID-19 Response Team; IVY Network.  Seroprevalence of SARS-CoV-2 among frontline health care personnel in a multistate hospital network—13 academic medical centers, April-June 2020.   MMWR Morb Mortal Wkly Rep. 2020;69(35):1221-1226. doi:10.15585/mmwr.mm6935e2PubMedGoogle ScholarCrossref
Anand  S , Montez-Rath  M , Han  J ,  et al.  Prevalence of SARS-CoV-2 antibodies in a large nationwide sample of patients on dialysis in the USA: a cross-sectional study.   Lancet. 2020;S0140-6736(20)32009-2. doi:10.1016/S0140-6736(20)32009-2PubMedGoogle Scholar
Rosenberg  ES , Tesoriero  JM , Rosenthal  EM ,  et al.  Cumulative incidence and diagnosis of SARS-CoV-2 infection in New York.   Ann Epidemiol. 2020;48:23-29.e4. doi:10.1016/j.annepidem.2020.06.004PubMedGoogle ScholarCrossref
Centers for Disease Control and Prevention. Commercial laboratory seroprevalence survey data. Accessed August 22, 2020.
Centers for Disease Control and Prevention. CDC COVID data tracker: nationwide commercial laboratory seroprevalence survey. Accessed November 2, 2020.
Office of the Federal Register and Government Publishing Office. Electronic code of federal regulations. Accessed November 2, 2020.
von Elm  E , Altman  DG , Egger  M , Pocock  SJ , Gøtzsche  PC , Vandenbroucke  JP ; STROBE Initiative.  The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies.   Ann Intern Med. 2007;147(8):573-577. doi:10.7326/0003-4819-147-8-200710160-00010PubMedGoogle ScholarCrossref
Prince  HE , Givens  TS , Lapé-Nixon  M ,  et al.  Detection of SARS-CoV-2 IgG targeting nucleocapsid or spike protein by four high-throughput immunoassays authorized for emergency use.   J Clin Microbiol. 2020;58(11):e01742-20. doi:10.1128/JCM.01742-20PubMedGoogle Scholar
Economic Research Service USDA. Rural-urban continuum codes. Accessed October 7, 2019.
Battaglia  MP , Hoaglin  DC , Frankel  MR .  Practical considerations in raking survey data.   Survey Practice. 2009;2(5):1. doi:10.29115/SP-2009-0019Google ScholarCrossref
United State Census Bureau. American community survey data. Accessed October 7, 2020.
Efron  B.   Bootstrap methods: another look at the jackknife.   The Annals of Statistics. 1979;7(1):1-26. doi:10.1214/aos/1176344552Google ScholarCrossref
Huang  AT , Garcia-Carreras  B , Hitchings  MDT ,  et al.  A systematic review of antibody mediated immunity to coronaviruses: kinetics, correlates of protection, and association with severity.   Nat Commun. 2020;11(1):4704. doi:10.1038/s41467-020-18450-4PubMedGoogle ScholarCrossref
USAFacts. US coronavirus cases and deaths. Accessed September 15, 2020.
Moscola  J , Sembajwe  G , Jarrett  M ,  et al; Northwell Health COVID-19 Research Consortium.  Prevalence of SARS-CoV-2 antibodies in health care personnel in the New York City area.   JAMA. 2020;324(9):893-895. doi:10.1001/jama.2020.14765PubMedGoogle ScholarCrossref
Dodd  RY , Xu  M , Stramer  SL .  Change in donor characteristics and antibodies to SARS-CoV-2 in donated blood in the US, June-August 2020.   JAMA. 2020. doi:10.1001/jama.2020.18598PubMedGoogle Scholar
Ward  H , Atchison  CJ , Whitaker  M ,  et al.  Antibody prevalence for SARS-CoV-2 in England following first peak of the pandemic: REACT2 study in 100,000 adults.   medRxiv. Posted online August 21, 2020. doi:10.1101/2020.08.12.20173690Google Scholar
Pollán  M , Pérez-Gómez  B , Pastor-Barriuso  R ,  et al; ENE-COVID Study Group.  Prevalence of SARS-CoV-2 in Spain (ENE-COVID): a nationwide, population-based seroepidemiological study.   Lancet. 2020;396(10250):535-544. doi:10.1016/S0140-6736(20)31483-5PubMedGoogle ScholarCrossref
Stringhini  S , Wisniak  A , Piumatti  G ,  et al.  Seroprevalence of anti-SARS-CoV-2 IgG antibodies in Geneva, Switzerland (SEROCoV-POP): a population-based study.   Lancet. 2020;396(10247):313-319. doi:10.1016/S0140-6736(20)31304-0PubMedGoogle ScholarCrossref
CDC COVID-19 Response Team.  Geographic differences in COVID-19 cases, deaths, and incidence—United States, February 12-April 7, 2020.   MMWR Morb Mortal Wkly Rep. 2020;69(15):465-471. doi:10.15585/mmwr.mm6915e4PubMedGoogle ScholarCrossref
Long  QX , Tang  XJ , Shi  QL ,  et al.  Clinical and immunological assessment of asymptomatic SARS-CoV-2 infections.   Nat Med. 2020;26(8):1200-1204. doi:10.1038/s41591-020-0965-6PubMedGoogle ScholarCrossref
Long  QX , Liu  BZ , Deng  HJ ,  et al.  Antibody responses to SARS-CoV-2 in patients with COVID-19.   Nat Med. 2020;26(6):845-848. doi:10.1038/s41591-020-0897-1PubMedGoogle ScholarCrossref
Zhao  J , Yuan  Q , Wang  H ,  et al.  Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019.   Clin Infect Dis. 2020;ciaa344. doi:10.1093/cid/ciaa344PubMedGoogle Scholar
Crawford  KHD , Dingens  AS , Eguia  R ,  et al.  Dynamics of neutralizing antibody titers in the months after SARS-CoV-2 infection.   J Infect Dis. 2020;jiaa618. doi:10.1093/infdis/jiaa618PubMedGoogle Scholar
Patel  MM , Thornburg  NJ , Stubblefield  WB ,  et al.  Change in antibodies to SARS-CoV-2 over 60 days among health care personnel in Nashville, Tennessee.   JAMA. 2020. doi:10.1001/jama.2020.18796PubMedGoogle Scholar
National SARS-CoV-2 Serology Assay Evaluation Group.  Performance characteristics of five immunoassays for SARS-CoV-2: a head-to-head benchmark comparison.   Lancet Infect Dis. Published online September 23, 2020. doi:10.1016/s1473-3099(20)30634-4.Google Scholar
Cheng  MP , Yansouni  CP , Basta  NE ,  et al.  Serodiagnostics for severe acute respiratory syndrome-related coronavirus 2 : a narrative review.   Ann Intern Med. 2020;173(6):450-460. doi:10.7326/M20-2854PubMedGoogle ScholarCrossref
Lerner  AM , Eisinger  RW , Lowy  DR ,  et al.  The COVID-19 serology studies workshop: recommendations and challenges.   Immunity. 2020;53(1):1-5. doi:10.1016/j.immuni.2020.06.012PubMedGoogle ScholarCrossref
Vardhana  SA , Wolchok  JD .  The many faces of the anti-COVID immune response.   J Exp Med. 2020;217(6):e20200678. doi:10.1084/jem.20200678PubMedGoogle Scholar
Stephens  DS , McElrath  MJ .  COVID-19 and the path to immunity.   JAMA. 2020;324(13):1279-1281. doi:10.1001/jama.2020.16656PubMedGoogle ScholarCrossref
Grifoni  A , Weiskopf  D , Ramirez  SI ,  et al.  Targets of T cell responses to SARS-CoV-2 coronavirus in humans with COVID-19 disease and unexposed individuals.   Cell. 2020;181(7):1489-1501.e15. doi:10.1016/j.cell.2020.05.015PubMedGoogle ScholarCrossref
Robbiani  DF , Gaebler  C , Muecksch  F ,  et al.  Convergent antibody responses to SARS-CoV-2 in convalescent individuals.   Nature. 2020;584(7821):437-442. doi:10.1038/s41586-020-2456-9PubMedGoogle ScholarCrossref
Okoro  CA , Zhao  G , Fox  JB , Eke  PI , Greenlund  KJ , Town  M .  Surveillance for health care access and health services use, adults aged 18-64 years—behavioral risk factor surveillance system, United States, 2014.   MMWR Surveill Summ. 2017;66(7):1-42. doi:10.15585/mmwr.ss6607a1PubMedGoogle ScholarCrossref
Centers for Disease Control and Prevention. CDC COVID data tracker: demographic trends of COVID-19 cases and deaths in the US reported to CDC. Accessed September 23, 2020.
Abrams  EM , Szefler  SJ .  COVID-19 and the impact of social determinants of health.   Lancet Respir Med. 2020;8(7):659-661. doi:10.1016/S2213-2600(20)30234-4PubMedGoogle ScholarCrossref
Lewis  NM , Friedrichs  M , Wagstaff  S ,  et al.  Disparities in COVID-19 incidence, hospitalizations, and testing, by area-level deprivation—Utah, March 3-July 9, 2020.   MMWR Morb Mortal Wkly Rep. 2020;69(38):1369-1373. doi:10.15585/mmwr.mm6938a4PubMedGoogle ScholarCrossref
Want full access to the AMA Ed Hub?
After you sign up for AMA Membership, make sure you sign in or create a Physician account with the AMA in order to access all learning activities on the AMA Ed Hub
Buy this activity
Want full access to the AMA Ed Hub?
After you sign up for AMA Membership, make sure you sign in or create a Physician account with the AMA in order to access all learning activities on the AMA Ed Hub
Buy this activity
With a personal account, you can:
  • Access free activities and track your credits
  • Personalize content alerts
  • Customize your interests
  • Fully personalize your learning experience
Education Center Collection Sign In Modal Right

Name Your Search

Save Search
With a personal account, you can:
  • Access free activities and track your credits
  • Personalize content alerts
  • Customize your interests
  • Fully personalize your learning experience

Lookup An Activity



My Saved Searches

You currently have no searches saved.


My Saved Courses

You currently have no courses saved.

With a personal account, you can:
  • Access free activities and track your credits
  • Personalize content alerts
  • Customize your interests
  • Fully personalize your learning experience
Education Center Collection Sign In Modal Right