Adverse Events Following COVID-19 Vaccination in Malaysia: A Cross-Sectional Study

Background: Vaccination remains the most effective strategy for controlling the COVID-19 pandemic. However, the COVID-19 vaccinations have been linked to a number of side effects. This study aimed to assess the frequency of vaccine-related adverse events among individuals in Malaysia. Methods: A cross-sectional, online questionnaire-based survey was conducted among vaccinated individuals in Malaysia from March to November 2024. Participants were recruited using a snowball sampling method, in which the initial respondents were invited through social media platforms and institutional networks and were encouraged to share the survey link with other eligible individuals. A 17-item self-administered questionnaire was designed, validated, and subsequently distributed through online platforms. The inclusion criteria encompassed Malaysian residents aged 18 years and above who had received at least one dose of a COVID-19 vaccine, were able to read and understand English or Malay, and provided informed consent prior to participation. Respondents were excluded if they were below 18 years of age, unvaccinated, or submitted incomplete or inconsistent responses. Result: Of 408 respondents, 288 (70.6%) reported experiencing side effects. Females (66.3%) and individuals aged 45–54 years (26.4%) were more likely to report adverse events. Fever was the most common side effect, with the highest proportion observed among Pfizer vaccine recipients (71.4%). The majority of participants (92%) reported only mild to moderate effects, such as fever and localized injection-site pain, which resolved without hospitalization. A substantial proportion (74.2%) of respondents reported prior COVID-19 infection. Conclusion: This study provides important insights into post-COVID-19 vaccination experiences in Malaysia. Most adverse events were mild and self-limiting, with only a small fraction requiring medical attention.