Abstract
INTRODUCTION: The global coronavirus disease 2019 (COVID-19) pandemic necessitated urgent vaccine development, raising concerns about potential vaccine adverse events (AEs). METHODS: In this prospective cohort study, conducted from February 2021 to December 2022, all individuals across Iran who received any COVID-19 vaccine dose and reported adverse events were investigated. Our aim was to evaluate these AEs based on the vaccine types, patients' age and types of AES, and provide a comprehensive analysis. RESULTS: In Iran, 155 million COVID-19 vaccine doses were administered, with Covilo (Sinopharm) being the most commonly vaccine administered (80.35%). Adverse events predominantly affected individuals aged 40-70 (45%). A total of 86,275 adverse events were recorded, with 92.7% classified as non-serious and 6 299 (7.3%) serious and among the serious cases, 279 were confirmed to be vaccine-related, with 46 resulting in fatalities and 233 requiring hospitalizations. The incidence of serious AEs was 0.41 per 10,000 doses. Serious AEs were more frequently associated with Sputnik V and Vaxzevria (AstraZeneca), with 0.73 and 0.64 cases per 10,000 injections, respectively. Coagulation and thrombosis disorders were the most common serious AEs (29%), followed by neurological (24.7%) and cardiovascular AEs (15.8%). DISCUSSION: In conclusion, the AEs of COVID-19 vaccination were primarily mild and transient, while serious AEs remained exceptionally rare.