COVID-19 Resource Center

COVID-19 Resource Center

Perspective from Gigi Kwik Gronvall, PhD
Disclosures: Jones reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
September 10, 2021
2 min read
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SARS-CoV-2 seroprevalence in US was 83% before surge of delta infections

Perspective from Gigi Kwik Gronvall, PhD
Disclosures: Jones reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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Based on testing of more than 1.4 million blood donations, researchers estimated that the SARS-CoV-2 seroprevalence from infection or vaccination among Americans aged 16 years or older was 83% in May, before the delta variant surge.

Jefferson M. Jones, MD, MPH, a medical officer at the CDC, and colleagues conducted a repeated cross-sectional study each month from July 2020 through May 2021 that tested specimens from 17 blood collection organizations with donations from all 50 states, Washington, D.C., and Puerto Rico.

Source: Adobe Stock.
SARS-CoV_2 seroprevalence from infection or vaccination reached 83% in May. Source: Adobe Stock.

After December, when the FDA authorized the first COVID-19 vaccines for use, they began testing specimens to differentiate whether seroprevalence was from infection or vaccination.

They included 1,443,519 blood donation samples in their analysis. Of these, 50.8% were from women, 12.1% were from people aged 16 to 29 years, and 20.2% were from people aged 65 years or older.

From July through December 2020, the estimated infection-induced seroprevalence among donors increased from 3.5% (95% CI, 3.2%-3.8%) to 11.5% (95% CI, 11.1%-11.8%), Jones and colleagues reported.

By May 2021, the combined seroprevalence among Americans had increased to 83.3% (95% CI, 82.9%-83.7%), and infection-induced seroprevalence increased to 20.2% (95% CI, 19.9%-20.6%), the researchers reported.

“Several large studies have shown that among individuals who are seropositive from prior SARS-CoV-2 infection, COVID-19 incidence is reduced by 80% to 95%, similar to vaccine efficacy estimates,” the authors wrote. “However, infection- and vaccination-induced protection might be reduced in the setting of SARS-CoV-2 variants, and infection-induced protection might wane more quickly than vaccine-induced protection.”

References:

Jones JM, et al. JAMA. 2021;doi:10.1001/jama.2021.15161.

CDC. COVID-19 Data Tracker. National Blood Donor Seroprevalence Survey. https://covid.cdc.gov/covid-data-tracker/#nationwide-blood-donor-seroprevalence. Accessed September 8, 2021.