Aims: To study adverse events following immunization of Covid-19 vaccines in people vaccinated from June 14, 2021 to March 13, 2022 at the vaccination center of University Hospital Yalgado Ouedraogo. Study Design: Our study was a descriptive and analytical cross-sectional study. Place and duration of study: Department of Medicine, from June 14, 2021 to March 13, 2022 at CHU-YO. Methodology: To identify the factors associated with the occurrence of adverse events following immunization, we used univariate binary logistic regression and a threshold of p < 0.2 was used for inclusion in the multivariate analysis. The significance threshold was then 0.05. We have obtained authorization to use the data from the ethics committee. Results: A total of 646 people were included. The mean age was 49.84 years [18 - 78 years]. The sex ratio (M/F) was 1.73. Health workers accounted for 32.2% of those vaccinated. Hypertension, allergy and diabetes were the most frequently reported medical conditions in 15.2%, 10.4% and 6.7% of those vaccinated respectively. Four hundred and forty-eight 448 (69.3%) presented at least one adverse event following immunization, of which 446 (99.6%) were minor and 2 (0.4%) major. Pain at the injection site, headache and fever accounted for 87.4%, 82.6% and 67.8% of cases respectively. The two major adverse events following immunization were anaphylactic shock and hemiparesis. In the majority of cases, adverse events following immunization occurred within 48 h of COVID-19 vaccination. Healthcare workers and history of allergy were statistically associated with the occurrence of adverse events following immunization. Conclusion: We need to study the adverse events following immunization associated with COVID-19 vaccines, in order to increase the population's adherence to the vaccine and better combat this Coronavirus pandemic.