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.