Kinetics of SARS-CoV-2 anti-S IgG after BNT162b2 vaccination

Deployment of the BNT162b2 mRNA Covid-19 Vaccine in Israel began in December 2020. This is a retrospective analysis of serological data, showing SARS-CoV-2 anti-S IgG kinetics in 116 Israeli health care workers receiving BNT162b2. Sero-conversion occurred in 14 days in all study participants, with IgG levels peaking approximately 30 days after initiation of the vaccination series. A statistically significant difference was observed in IgG levels between subjects younger than 50 years and older participants, although in all cases, IgG levels were well above the level considered reactive by the test's manufacturer. The importance of this difference needs to be studied further, but a potential difference in vaccine efficacy and vaccine effect length could possibly be present between these two groups.