Correlation of Anti-SARS-CoV-2 S1-specific IgG antibody levels and adverse events following vaccination with BNT162b2 mRNA COVID-19 vaccine in healthcare workers

Currently approved anti-COVID-19 vaccines have been found to be safe and effective and almost 60% of Israeli residents are already vaccinated with BNT162b2 vaccine. This observational study was designed to evaluate the adverse events of vaccine reported by 61 healthcare workers at least 7 days after the 2nd vaccination, and to investigate the correlation of adverse events and anti-SARS-CoV-2 IgG antibody levels. The median participant's age was 51.25 years, 16 men and 45 women; 77% (44% of male and 84.5% of female participants) reported adverse events. Injection site pain, fatigue and fever were the most common symptoms, and significantly higher antibody levels (average 19,387 AU/mL) were found in participants who had fever compared to those who did not experience fever (average antibody levels of 9,977 AU/mL, p < 0.001). This finding corresponds to previous observations of higher anti-SARS-CoV-2 IgG antibody levels in COVID-19 patients presented with fever.