COVID 19 convalescent plasma donors: impact of vaccination on antibody levels, breakthrough infections and reinfection rate.
From April 2020 through May 2021 in Padova Province 3395 COVID 19 recovered patients were recruited as potential convalescent plasma donors and tested for SARS CoV 2 antibodies. Since January 2021 COVID 19 vaccination campaign began in Italy, the impact of vaccination on antibody levels and suspect vaccine breakthrough infections in these subjects were investigated. Post vaccination anti Sars Cov 2 antibody level in 54 previously infected subjects had an exponential increase compared to pre vaccination level regardless of the number of vaccine doses. However after 100 days from vaccination SARS CoV 2 antibody level tends to decline. Post vaccination primary infections were detected in 15 cases, with 3 possible breakthrough infections after a full vaccination course. In these cases, antibody response after infection was present but weaker than the one of subjects vaccinated after natural infection. A trend toward stronger antibody response was observed with increasing distance between natural infection and vaccination. Additionally, 2 cases of asymptomatic reinfections are also discussed.
medRxiv