Adverse Events Following mRNA COVID-19 Vaccine in 2021 and 2022: A Retrospective Analysis in Costa Rica and Italy.

Introduction Pharmacovigilance plays a crucial role in evaluating and monitoring the safety of medicines, which is essential for preventing harm to patients and improving public health. This study aims to compare the pharmacovigilance systems of Costa Rica and Italy and assess the safety profile of coronavirus disease 2019 (COVID-19) vaccines in both countries. Methods Data were collected from the official pharmacovigilance platforms in Costa Rica and Italy. Adverse events following immunization (AEFIs) were categorized by system organ class. Reports of suspected AEFIs associated with COVID-19 vaccines were analyzed for the period from January 1, 2021, to December 31, 2022. Results Both countries achieved high vaccination rates, with 84.9% in Italy and 92.9% in Costa Rica. A higher proportion of AEFIs occurred in females in both countries, with 53% and 65% in Naples and Costa Rica, respectively. Most AEFIs were observed in individuals aged 18-64 years. The rate of serious adverse reactions was lower in both countries than the international average. However, Naples reported a higher incidence of serious events per 100,000 inhabitants. Discussion The study sheds light on the importance of vaccine safety profiling and the significance of a comprehensive understanding of vaccine safety and effectiveness, specific population data, and collaborative strategies to mitigate and improve safety. Additionally, the study highlighted the significance of considering sex and gender when evaluating vaccine safety and efficacy, as sex-specific differences may impact vaccine outcomes. Conclusion Continuous pharmacovigilance efforts, collaborative approaches, and comprehensive data analysis are critical in ensuring vaccine safety and efficacy and safeguarding global public health. Lessons learned from the COVID-19 pandemic highlight the importance of proactive measures in addressing emerging challenges in vaccine safety and rollout programs worldwide.