Importance People who have been infected with or vaccinated against SARS-CoV-2 have
reduced risk of subsequent infection, but the proportion of people in the US with SARS-CoV-
2 antibodies from infection or vaccination is uncertain. Objective To estimate trends in SARS-
CoV-2 seroprevalence related to infection and vaccination in the US population. Design,
Setting, and Participants In a repeated cross-sectional study conducted each month during
July 2020 through May 2021, 17 blood collection organizations with blood donations from all …