Abstract
Background The administration of COVID-19 vaccines has been critical in controlling the spread of the virus. However, understanding the potential adverse events (AEs) associated with these vaccines is crucial for public health. While most previous studies observed only short-term AEs, this study aimed to investigate the immediate and long-term AEs following the first and second doses of Pfizer, AstraZeneca, and Sinopharm vaccines, providing valuable long-term insights. Methodology A prospective, one-year, follow-up study was conducted by tracking 922 vaccinated individuals to assess short-term and long-term AEs. Demographics, clinical characteristics, vaccine types, and dose effects were taken into consideration. AEs were classified based on severity and duration. Statistical analyses were performed to compare differences among the vaccine groups, with p-values <0.05 considered significant. Bowker's and chi-square tests were performed using JMP Pro 14.3.0. Results Of the 922 participants, 55.53% (n = 512) were vaccinated with Pfizer, and 23.32% (n = 215) and 21.15% (n = 195) were vaccinated with Sinopharm and AstraZeneca, respectively. Overall, 72.34% of participants (n = 667) were suffering from AEs after the first dose, with a lower prevalence of AEs after the second dose (52.71%, n = 486). Pfizer exhibited the highest percentage and severity of AEs, followed by AstraZeneca and Sinopharm. Most AEs reported in this study were mild and resolved within 72 hours, with females experiencing more frequent AEs. The common short-term AEs observed were fever, injection-site pain, myalgia, fatigue, and headache. Notably, there were no chronic AEs, and only one case of myocarditis was associated with AstraZeneca. Conclusions Despite the variation in the prevalence of AEs among the three vaccines, the vaccination process proved to be safe with no serious short-term AEs. However, the long-term AEs associated with AstraZeneca and the decrease in the prevalence of AEs after the second dose of the COVID-19 vaccines warrant further investigations and priority for future research.