Active Surveillance of Adverse Events in Healthcare Workers Recipients After Vaccination with COVID-19 BNT162b2 Vaccine (Pfizer-BioNTech, Comirnaty): A Cross-Sectional Study

Abstract

In this cross-sectional study, adverse events after the first and second dose of BNT162b2 mRNA (Pfizer-BioNTech, Comirnaty) vaccine against coronavirus disease 2019 were investigated among employees of clinics in central Italy. A 42-items questionnaire was administrated to vaccine recipients. Adverse events were classified based on severity and occurrence as reported in the literature. A descriptive/univariate analysis using Chi-square or Fisher's Exact tests was performed. Odds ratio (OR) and 95% confidence intervals were calculated to assess risk factors. 340 individuals (61.5% females; median age 49 years) participated. Adverse events were reported by 279 (82%) and 281 (82.6%) individuals as induced by the first and second dose, respectively. Mild reactions were mainly reported (80.9% and 80.3%), followed by moderate (11.8% and 37.1%) and severe (3.8% and 4.7%). Adverse events were identical to those already described as very common (81.8% and 80.6%), although vaccine-coincidental events not cited in the literature were reported by 6% and 15.6% following each dose. Age ≤ 55 years was a risk factor for any adverse event after each injection (ORs: 2.942 and 2.818), as well as female sex for those mild (ORs: 1.856 and 2.818) and common (ORs: 3.452 and 2.145). Findings were consistent with national reports as most of the adverse events were mild and associated with female sex and young age, while investigations are needed for reactions not described elsewhere. Data are useful to support the vaccine safety profile, also because largely targeted healthcare personnel more skilled than general population in self-diagnosis of health-related issues.

Keywords: BNT162b2 mRNA vaccine; First dose; Safety; Second dose; Sex differences; Younger adults.