Antibody titers decline 3-month post-vaccination with BNT612b2

Abstract

\n Introduction: Several studies reported on the humoral response in subjects having received theBNT162b2 mRNA COVID-19 vaccine. However, data on the kinetics of antibodies 3 months postvaccinationare currently lacking and are important to drive the future vaccination strategy.Methods: The CRO-VAX HCP study is an ongoing multicenter, prospective and interventional studydesigned to assess the antibody response in a population of healthcare professionals who had receivedtwo doses of the BNT162b2 mRNA COVID-19 vaccine. Two-hundred individuals underwent a blooddrawn within 2 days before the first vaccine dose. One-hundred and forty-two persons (71%) werecategorized as seronegative at baseline while 58 (29%) were seropositive. Samples were then collectedafter 14, 28, 42, 56, and 90 days. Antibodies against the SARS-CoV-2 nucleocapsid and the receptorbinding domain of the S1 subunit of the spike protein were measured in all individuals at different timepoints.Results: Using a one-compartment kinetics model, the time to maximum concentration was estimatedat 36 ± 3 days after the first dose and the estimated half-life of antibodies was 55 days (95% CI: 37-107days) in seronegative participants. In seropositive participants, the time to maximum concentrationwas estimated at 24 ± 4 days and the estimated half-life was 80 days (95% CI: 46-303 days). Theantibody response was higher in seropositive compared to seronegative participants.Conclusion: In both seropositive and seronegative subjects, a significant antibody decline wasobserved at 3 months compared to the peak response. Nevertheless, the humoral response remainedrobust in all participants.