Impact of BNT162b2 Booster Dose on SARS-CoV-2 Anti-Trimeric Spike Antibody Dynamics in a Large Cohort of Italian Health Care Workers

Accurate studies on the dynamics of Pfizer-Biontech BNT162b2-induced antibodies are crucial to better tailor booster dose administration depending on age, comorbidities, and previous natural infection with SARS-CoV-2. To date, little is known about the durability and kinetics of antibody titers months after receiving a booster dose. In this work, we studied the dynamic of anti-Trimeric Spike (anti-TrimericS) IgG titer in the healthcare worker population of a large academic hospital in Northern Italy, in those who had received two vaccine doses plus a booster dose. Blood samples were collected on the day of dose 1, dose 2, then 1 month, 3 months, and 6 months after dose 2, the day of the administration of the booster dose, then 1 month and 3 months after the booster dose. The vaccination immunogenicity was evaluated by dosing anti-TrimericS IgG titer, which was further studied in relation to SARS-CoV-2 infection status, age, and sex. Our results suggest that after the booster dose, the anti-TrimericS IgG production was higher in the subjects that were infected only after the completion of the vaccination cycle, compared to those that were infected both before and after the vaccination campaign. Moreover, the booster dose administration exerts a leveling effect, mitigating the differences in the immunogenicity dependent on sex and age.