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

Abstract

SARS-CoV-2 is a novel human pathogen, causing Coronavirus Disease 2019 with widespread global morbidity and mortality. Since health care workers (HCW) in Israel were among the first to be vaccinated in December 2020, we had a unique opportunity to investigate the post-vaccination level of IgG anti-S antibodies, rate of decline, and association with demographic and professional factors. Prospective Serological Survey during December 2020–August 2021 at Barzilai Medical Center among 458 HCW followed for 6 months after the second BNT162b2 vaccine dose. Antibody levels 0-5 days before the second dose, and 30, 90 and 180 days after afterwards were 57.1±29.2, 223±70.2, 172.8±73.3 and 166.4±100.7 AU/ml, respectively. From GEE model, females had higher level of antibodies (β=26.37 AU/ml, p=0.002). Age was negatively associated with antibodies9 titers, with a 1.17 AU/ml decrease for each additional year (p<0.001). Direct contact with patients was associated with lower antibodies9 level by 25.02 AU/ml (p=0.009) as compared to working with no direct contact. Average decline rate of level antibodies over 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 compared to the subsequent 3 months. All demographic groups experienced a decline in level of antibodies over time, faster during the first 3 months. Findings of overall antibodies lower in males, workers with direct contact with patients and older workers, should be taken into account for policy making about choosing priority populations for additional vaccine doses in community HCW.