Immunogenicity trends one and three months after second BNT162B2 vaccination among healthcare workers in Israel

Objectives We evaluated antibody response to the BNT162B2 vaccine among healthcare workers (HCWs) to identify factors associated with decreased immunogenicity. Methods This prospective cohort study included consenting HCWs who completed a questionnaire regarding background illnesses, medications, and post vaccination allergic reactions or rash. All HCWs were tested for anti-spike antibodies (LIAISON SARS-CoV-2 S1/S2 IgG assay) one and three months after second vaccine dose. A multivariate mixed linear model was adjusted to participant’s data and fit to predict antibody levels after second BNT162B2 vaccine dose, based on antibody levels at 1 month and the slope between 3 and 1 month. Multivariate analyses identified factors associated with lower antibody levels. Results A total of 1,506 HCWs were tested for SARS-CoV-2 antibodies. Older age was associated with lower mean antibody levels (-1.22 AU/ml, p
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