In the first week of March, over 20% of blood donations from unvaccinated people were found to have COVID-19 antibodies, report data from the American Red Cross.

From the mid of June 2020 to early March 2021, the American Red Cross assessed over 3.3 million donations from unvaccinated people across 44 states for the presence of COVID-19 antibodies. Nearly 7.5% of the donations tested in that time frame had COVID-19 antibodies, thus suggesting that the donors had likely been infected with COVID-19 at some point. Nearly 1.5% of donations tested in the first week of July were found to be positive, rising to around 4% of donations tested in the first week of October. It increased to around 12% of donations tested in the first week of January and about 21% of donations tested in the first week of March… (CNN, March 16, 2021)