The descriptive epidemiology of adverse events following two doses of mRNA COVID-19 vaccination in Curaçao, the Caribbean.

Background: BNT162b2 and mRNA-1273 COVID-19 vaccines have been used for mass vaccinations in Curaçao, the Caribbean but information on adverse events (AEs)in this population is unavailable. This study describes the characteristics of vaccinees that incurred AEs, explores the associations between AEs by vaccine and doses, and estimates the rate of AEs.

Methods: Vaccination and AEs data for all persons of age 5 years (range 5-105 years) and older who received two doses of COVID-19 vaccine at 71 centres in Curaçao between February 24, 2021, and April 5, 2023, were included in this retrospective observational study.

Results: The vaccines differed significantly in the frequency distribution of vaccinees by age, age groups, sex, AEs, and prior COVID-19 infection. Occurrence of AEs was strongly associated with mRNA vaccine brand, sex, number of doses, but not with age, age group, and prior COVID-19 infection. Of 209,720 doses, 84 persons (0.04%) incurred AEs following two doses of mRNA vaccines (overall rate of 40.1 per 100,000 persons (95% CI 32.4-49.6). AEs were also significantly higher in females compared to males.AE rates associated with BNT162b2, and mRNA-1273 vaccines were low, but BNT162b2 vaccinees incurred substantially significantly higher AE rates (58.3 per 100,000 persons, 95% CI 45.4-74.9) than mRNA-1273 vaccinees (21.9 per 100,000 persons, 95% CI 14.6-32.8). mRNA-1273 vaccine was associated with a significantly lower risk of AEs.

Conclusions: AE reporting varied by age, sex, and vaccine used as well as the number of doses. Future studies with follow-up and longer-term reporting of AEs should be conducted.