BackgroundThere are various COVID-19 vaccines launched in different parts of the world. As the vaccination drive is increasing, the reports of adverse events following immunization (AEFI) are increasingly reported. Therefore, this research aims to document the adverse events and their determinants following COVID-19 vaccination. MethodsThis was a cross-sectional study conducted in a primary healthcare setting of Western Nepal. Those individuals who took the first dose of the ChAdOx1 nCoV-19 vaccine in the health care center (N=425) were eligible for the study. The details to contact the study participants were obtained from the vaccination center. Patients were contacted via phone calls by investigators. Information on demographic details, comorbidities and experiences of any sort of adverse events following vaccination was collected using pre-structured questionnaire. Descriptive statistics was done to describe the categorical variables in frequency and percentage whereas mean, median, standard deviation and interquartile range were calculated for quantitative variables. Binary logistic regression was carried out to explore the potential determinants of AEFI.