Factors influencing COVID-19 vaccination acceptance when knowing potential side effects: a study in Colombia.

Aim: To examine the determinants of COVID-19 vaccine acceptance in Colombia, with particular emphasis on individuals' responses to possible side effects. Methods: A cross-sectional study was conducted using an anonymous online questionnaire in Colombia between January and March 2023. The Results: The 40.2% of respondents expressed doubts or would have rejected vaccination had they known about possible side effects beforehand. Women were more likely to hold doubts or reject the vaccine after experiencing adverse effects. Participants who experienced side effects were more likely to question their decision to vaccinate. Younger individuals were less likely than older adults to develop negative attitudes after experiencing side effects. Those who had received only one dose were more likely to doubt or reject further vaccination, whereas individuals with multiple doses were less likely to do so. Participants with asymptomatic COVID-19 were less likely to refuse vaccination after learning about potential side effects, possibly because they trusted their immune system more or had a stronger desire to protect others. Conclusions: Vaccination hesitancy was associated with female sex, prior adverse effects, and fewer doses, whereas younger age was associated with greater acceptance. These findings highlight the need for targeted risk communication to address safety concerns and strengthen vaccine confidence.