Naturally Acquired SARS-CoV-2 Immunity Persists for Up to 11 Months Following Infection

Background. Characterizing the kinetics of the antibody response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is of critical importance to developing strategies that may mitigate the public health burden of coronavirus disease 2019 (COVID-19). We conducted a prospective, longitudinal analysis of COVID-19 convalescent plasma donors at multiple time points over an 11-month period to determine how circulating antibody levels change over time following natural infection. Methods. From April 2020 to February 2021, we enrolled 228 donors. At each study visit, subjects either donated plasma or had study samples drawn only. Anti-SARS-CoV-2 donor testing was performed using the VITROS Anti-SARS-CoV-2 Total and IgG assays and an in-house fluorescence reduction neutralization assay. Results. Anti-SARS-CoV-2 antibodies were identified in 97% of COVID-19 convalescent donors at initial presentation. In follow-up analyses, of 116 donors presenting at repeat time points, 91.4% had detectable IgG levels up to 11 months after symptom recovery, while 63% had detectable neutralizing titers; however, 25% of donors had neutralizing levels that dropped to an undetectable titer over time. Conclusions. Our data suggest that immunological memory is acquired in most individuals infected with SARS-CoV-2 and is sustained in a majority of patients for up to 11 months after recovery.