ChAdOx1 nCoV-19 vaccine and its self-reported adverse events: a cross-sectional study from Western Nepal

# Background There 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. # Methods This 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. # Results A total of 302 (71.05%) people were randomly selected from 425 targeted people for vaccination at the primary health care center. A total of 276 (91.3%) people vaccinated with ChAdOx1 nCoV-19 vaccine responded to telephone call. Mean age of participants was 33.63 (± 11.14) years and majority of them were males (54.74%). 91.6% of participants developed some form of AEFI. Among them, 46.6% developed mild AEFI, and 53.4% developed moderate AEFI. Pain on the injection site, generalized weakness, fever, headache, joint and muscle pain, dizziness, and loss of appetite are found to be the “Very common” adverse events. Females tend to develop moderate AEFI than males (OR 2.369; 95% confidence interval, CI=1.398-4.014; *P*=0.001). Age did not seem to be the determinant of AEFI (OR 0.977; CI=0.954-1.002; *P*=0.067). # Conclusions Adverse events following COVID-19 immunization are common but not severe. The severity of AEFI is more in females compared to males. Age did not come out as a predictor for severity of AEFI. Post-vaccination counseling targeting women will improve the acceptance of the vaccine. We recommend further monitoring of AEFI in larger population.