Infectious Disease

The US SARS-CoV-2 seroprevalence was 83% prior to the rise in Delta infections

September 10, 2021

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Jones does not report any relevant financial information. Please refer to the study for all relevant financial information from the other authors.

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Based on testing of more than 1.4 million blood donations, researchers estimated that SARS-CoV-2 seroprevalence due to infection or vaccination in Americans 16 years of age or older was 83% in May prior to the delta variant surge.

Jefferson M. Jones, MD, MPH, a CDC medical officer, and colleagues conducted a repetitive cross-sectional study every month from July 2020 to May 2021, testing samples from 17 blood collection organizations with donations from all 50 states, Washington, DC and Puerto Rico.

Source: Adobe Stock.

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

After the FDA approved the first COVID-19 vaccines for use in December, they began testing samples to distinguish whether the seroprevalence was from infection or vaccination.

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

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

By May 2021, the combined seroprevalence among Americans was 83.3% (95% CI, 82.9% -83.7%) and the infection-induced seroprevalence was 20.2% (95% CI, 19.9% ​​-20 , 6%), the researchers reported.

“Several large studies have shown that people who are seropositive from previous SARS-CoV-2 infection have an 80% to 95% reduction in COVID-19 incidence, similar to vaccine effectiveness estimates,” write the authors. “However, the infection- and vaccine-induced protection could be reduced in the context of SARS-CoV-2 variants and the infection-induced protection could decrease faster than the vaccine-induced protection.”

References:

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

CDC. COVID-19 data tracker. National survey on the seroprevalence of blood donors. https://covid.cdc.gov/covid-data-tracker/#nationwide-blood-donor-seroprevalence. Retrieved September 8, 2021.

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Gigi Kwik Gronvall, PhD

This is a very interesting paper that has a lot of information on who has already had COVID-19 – more than has been reported to health officials – and been vaccinated. There is a lot of interesting data out there, but the hope is that we will peak in Delta infections sooner than reported cases suggest, as there are more people who may have some immunity.

There are many caveats, but the bottom line is that these studies aid in public health decision-making and help determine where resources should be targeted. The study shows that older people, for example, have more vaccination protection and younger people have higher rates of infection-related antibodies. We know there needs to be more vaccination effort for younger people.

Gigi Kwik Gronvall, PhD

Senior scholarship holder

Johns Hopkins Center for Health Safety

Associate professor

Department of Environment, Health and Engineering

Johns Hopkins Bloomberg School of Public Health

Disclosure: Gronvall does not report any relevant financial information.

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