Abstract
Background Vaccination is a cornerstone of COVID-19 control, yet concerns about side effects continue to influence acceptance. Evidence from medical students in low- and middle-income countries is limited, despite their future role in guiding public attitudes. Methods A cross-sectional online survey was conducted among undergraduate medical students in Bangladesh between February 2021 and April 2022. Data on demographics, vaccination history, and post-vaccination symptoms were collected through a structured questionnaire. Descriptive statistics, chi-square tests, and multivariable Firth logistic regression were used to examine associations between sex, vaccine type, and side effects. Results Of 305 respondents (mean age = 21.6 years; 196 females, 64.3%), 293 (96.1%) and 286 (93.8%) received the first and second vaccine doses, respectively, while 191 (62.6%) received a third dose. The most common vaccines were Sinopharm (125 participants, 41.0%), Pfizer-BioNTech (68 participants, 22.3%), and Moderna (60 participants, 19.7%). Overall, 276 participants (90.5%) experienced at least one side effect, with the prevalence declining across doses: 270 (88.5%) after the first dose, 243 (79.7%) after the second dose, and 128 (42.0%) after the third dose. The most frequent complaints were local pain (508 cases, 41.2%), fever (184, 14.9%), rash or itch (114, 9.2%), headache (108, 8.8%), and myalgia (103, 8.3%). Less common outcomes included anxiety or low mood (70, 5.7%) and alopecia (45, 3.6%), while serious events were rare. Female participants had higher odds of experiencing second-dose side effects (OR: 1.85, 95% CI: 1.05-3.26). Compared with Moderna, Pfizer-BioNTech was associated with fewer third-dose events (OR: 0.45, 95% CI: 0.21-0.94). Conclusion COVID-19 vaccines were well-tolerated among Bangladeshi medical students, with most side effects mild and self-limiting. Reactogenicity declined with subsequent doses and varied by sex and vaccine type. These results emphasize the need for transparent communication and vaccine literacy within medical education to enhance students' confidence and their role in addressing vaccine hesitancy.