Research suggests that more than 80% of American adults have COVID19 antibodies earned either through vaccination or infection. The study is based on data gathered from blood donors, estimating that 80% of Americans aged 16 and above have COVID antibodies as of May 2021.

Analyzing Blood Donations for SARS-CoV-2 Antibodies

(Photo: Sarah Chai from Pexels)

In the study published in the journal JAMA, titled "Estimated US Infection- and Vaccine-Induced SARS-CoV-2 Seroprevalence Based on Blood Donations, July 2020-May 2021," researchers from different blood donation organizations, in collaboration with the Centers for Disease Control and Prevention's pandemic response team, analyzed blood donations beginning July 2020. Collecting from Americans over the age of 16, the researcher searched for the prevalence of COVID-19 antibodies.

Samples were gathered from all 50 states, from areas that represented roughly 74% of the U.S. population. After the start of vaccination campaigns in December 2020, researchers added a secondary test to differentiate between positive antibody results due to infection or vaccine-induced. By May 2021, the team has collected a little under 1.5 million blood samples, reports Gizmodo.

Using the blood samples collected as a baseline, the team estimates that roughly 3.5% of Americans over 16 years of age developed antibodies of COVID19 by July 2020 via infection. By May of 2021, the number of Americans with infection-induced antibodies grew to roughly 20.2%, and when combining both immunity types, the team estimated that roughly 83.3% of adults have SARS-CoV-2 antibodies.

Authors wrote that based on the samples of blood donations collected from July 2020 to May 2021, vaccine- and infection-induced COVID-19 seroprevalence increased over time and varied by race, age, ethnicity, and geographic region.

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Limitations, Restrictions of Research

The results come with specific crucial limitations. Those who donated blood may differ from the general public in very relevant ways that could affect their likelihood of getting infected or vaccinated.

Additionally, since the samples were from U.S. adults over the age of 16, it does not tell us the prevalence of antibodies in younger members of the population.

Moreover, antibody tests are not without flaws; some unlucky people may not have generated detectable antibodies after infection or vaccination. Likewise, immunity is more complex than simply having the right antibodies.

Another source of error is that millions of Americans have been either vaccinated or infected since the end of May, meaning the estimates are most likely to be lower than the current percentage of American adults with COVID-19 antibodies.

On the other hand, the authors tried to account for differences between the general public and blood donors in calculating their estimates. However, the team acknowledges that their math may have come short.

Authors wrote in the study that despite attempting to weigh and adjust for demographic differences, the findings from national samples may not be truly representative of the entire U.S. population.

In conclusion, the numbers derived from the year-long analysis should be seen as a rough sketch for the population's collective immunity against the coronavirus, despite the figures not being exact.

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