Safety and side effect profile of Pfizer-BioNTech COVID-19 vaccination among healthcare workers: A tertiary hospital experience in Singapore

: Vaccination remains a key strategy to living endemically with COVID-19. ThePfizer-BioNTech COVID-19 vaccine was first granted interim authorisation for use in Singapore inDecember 2020. With overseas studies published about the safety and side effect profiles of mRNACOVID-19 vaccines focusing mainly on non-Asian populations, we described the side effects ofPfizer-BioNTech COVID-19 vaccination experienced by the healthcare workers (HCWs) in a tertiaryhospital in Singapore.Methods: Data were obtained from the Occupational Health Clinic (OHC) at the National UniversityHospital in Singapore, which monitored staff for any adverse effects within 30 minutes postvaccinationon-site and any adverse effects after that. A cross-sectional study among the vaccinatedHCWs was conducted using an online survey, which established basic demographics, histories ofallergies or atopic disorders, and adverse events encountered after dose 1 and dose 2 of vaccination.Results: No anaphylaxis was reported. Most common symptom was giddiness (32.7%) experiencedby HCWs within 30 minutes. Adverse events attended post-vaccination by OHC were generally mildand self-limiting. From the survey, odds of experiencing an adverse event after dose 2 was significantlyhigher than after the first dose, especially for fever/chills (odds ratio [OR] 22.5). Fever/chills, injectionsite reactions, headache, aches and pains, and feeling unwell were significantly more common inHCWs below 60 years compared to those ≥60 years. An allergy to food (adjusted OR 2.7) and a historyof eczema/sensitive skin (adjusted OR 2.6) were associated with a skin reaction not at injection site.Conclusion: The side effects experienced after Pfizer-BioNTech COVID-19 vaccines are generallyself-limiting and mild, with no anaphylaxis reported.Keywords: COVID-19, infectious diseases, occupational medicine, side effects, vaccination