Abstract

Objectives: In the context of the SARS-CoV-2 pandemic, it is important to better understand whether and, more importantly, how long individuals who were administered a SARS-CoV-2 vaccination are protected from future infections. Healthcare workers are at permanent risk of exposure to SARS-CoV-2-safe and lasting vaccination response is therefore of immense importance. The aim of the present work is to record antibody titer against SARS-CoV-2 in a large cohort of vaccinated employees at the university hospital over time and to identify possible factors influencing antibody formation.

Methods: We retrospectively analyzed a cohort of 1045 employees who received vaccination against SARS-CoV-2 during the course with BNT162b2 vaccine from Biontech/Pfizer. Blood was drawn from the employees at predefined time points and analyzed for the presence of SARS-CoV-2 antibodies (IgG) against the Receptor Binding Domain (RBD) of the Spike protein (S). In addition, all participants completed a questionnaire.

Results: A total of 863 females (82.6%) and 182 males (17.4%) were screened. The mean antibody titer was 69127.8 BAU/ml (SD=69319.6 BAU/ml) in female participants and 60867.8 BAU/ml (SD=65249.6 BAU/ml) in male participants. There was no significant difference concerning gender and antibody levels (p=0.071). In a multivariate analysis, we found a significant influence of age on the antibody formation (p<0.001); the older the participants, the lower the antibody level. The highest antibody levels were detected in study participants 30-50 days after their first vaccination. 50 days after vaccination only lower antibody titer in proband could be detected.

Conclusion: In the large cohort of 1045 health care workers, a high heterogeneity of antibody titers was observed. There is a significant influence of age on antibody levels-older employees had a lower antibody titer. 50 days after vaccination only lower antibody titer in proband could be detected.

Keywords: Immune response; SARS-CoV-2; Antibodies; Vaccination