J Infect Dis. 2021 Jun 5:jiab295. doi: 10.1093/infdis/jiab295. Online ahead of print.
BACKGROUND: Characterizing the kinetics of the antibody response to SARS-CoV-2 is of critical importance to developing strategies that may mitigate the public health burden of COVID-19. We conducted a prospective, longitudinal analysis of COVID-19 convalescent plasma (CCP) donors at multiple time points over an 11-month period in order 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 (FRNA).
RESULTS: Anti-SARS-CoV-2 antibodies were identified in 97% of COVID-19 convalescent donors at initial presentation. In follow up analyses, of the 116 donors presenting for repeat timepoints, 91.4% of donors had detectable IgG levels up to 11 months post-symptom recovery, while 63% had detectable neutralizing titers, however, we observed that 25% of donors had neutralizing levels that dropped to an undetectable titer over time.
CONCLUSION: 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.