One-year dynamics of antibody titers after three doses of SARS-CoV-2 BNT162b2 vaccine.

BACKGROUND: A third dose of the BNT162b2 SARS-CoV-2 vaccine leads to a significant increase in antibody levels, however, concerns regarding the long-term persistence of this response exist. We assessed the humoral response for one year following vaccination. METHODS: A prospective study among immunocompetent healthcare workers (HCW) who received three doses of BNT162b2. anti-spike antibody titers were measured at six predefined timepoints, from before the second vaccine dose, and up to one year afterwards, which is 4-6 months after the third dose. HCW with a history of SARS-CoV-2 infection were excluded. RESULTS: Seventy-six HCW had all the six serological measurements. Antibody titers significantly increased shortly following the third vaccine dose, and while declining, remained higher from all previous measurements for up to six months. CONCLUSIONS: A third dose of BNT162b2 leads to a profound humoral response, which remains significantly higher than previous measurements, even after 6 months.

Assessment of Predictors for SARS-CoV-2 Antibodies Decline Rate in Health Care Workers after BNT162b2 Vaccination-Results from a Serological Survey.

BACKGROUND: SARS-CoV-2 is a novel human pathogen causing Coronavirus Disease 2019 that has caused widespread global mortality and morbidity. Since health workers in Israel were among the first to be vaccinated, we had a unique opportunity to investigate the post-vaccination level of IgG anti-S levels antibodies (Abs) and their dynamics by demographic and professional factors. METHODS: Prospective Serological Survey during December 2020-August 2021 at Barzilai Medical Center among 458 health care workers (HCW) followed for 6 months after the second BNT162b2 vaccine dose. RESULTS: Antibody levels before the second dose, and 30, 90 and 180 days after were 57.1 ± 29.2, 223 ± 70.2, 172.8 ± 73.3 and 166.4 ± 100.7 AU/mL, respectively. From GEE analysis, females had higher Abs levels (ß = 26.37 AU/mL, p = 0.002). Age was negatively associated with Abs, with a 1.17 AU/mL decrease for each additional year (p < 0.001). Direct contact with patients was associated with lower Abs by 25.02 AU/mL (p = 0.009) compared to working with no such contact. The average decline rate overall for the study period was 3.0 ± 2.9 AU/mL per week without differences by demographic parameters and was faster during the first 3 months after vaccination than in the subsequent 3 months. CONCLUSIONS: All demographic groups experienced a decline in Abs over time, faster during the first 3 months. Findings of overall Abs lower in males, workers with direct contact with patients, and older workers, should be considered for policy-making about choosing priority populations for additional vaccine doses in hospital settings.