In the first week of March, more than 20% of blood donations from unvaccinated people had Covid-19 antibodies, according to data shared with CNN by the American Red Cross.
Between mid-June 2020 and early March 2021, the American Red Cross tested more than 3.3 million donations from unvaccinated people in 44 states for the presence of Covid-19 antibodies. Overall, about 7.5% of the donations tested in that time frame were positive for Covid-19 antibodies, meaning the donors had likely been infected with the coronavirus at some point.
The American Red Cross notes that “a positive antibody test result does not confirm infection or immunity,” but it may indicate whether a person has been exposed to the coronavirus, “regardless of whether an individual developed symptoms.” The antibody prevalence among unvaccinated blood donors increased over time, as cases grew across the country.
According to data shared with CNN over email, about 1.5% of donations tested in the first week of July were positive for Covid-19 antibodies. That increased to nearly 4% of donations tested in the first week of October, about 12% of donations tested in the first week of January and nearly 21% of donations tested in the first week of March.