Objective: Vaccines are one of the promising approaches to control the pandemic. The aim of this study, which was conducted on healthcare workers who previously were or were not infected with COVID-19, was to evaluate the un- desirable effects that developed after the CoronaVac (Sinovac Life Sciences, Beijing, China). Methods: Volunteers who were administered the first dose of inactivated CoronaVac vaccine between January 14-24, 2021, were included in this retrospective study. Demographic information was obtained from the questionnaire results and from the data of the applications made due to side effects. Results: 911 healthcare workers, 232 of whom had a history of COVID-19 were included in the study. The mean age of those with a history of COVID-19, was 36 (20-66), and 33.6% were men. 26.7% were doctors, 34.9% were nurses, 155 (66.8%) worked in internal and 62 (26.7%) in surgical units. There was no significant difference between the two groups regarding age, gender, task, and the departments they worked in. Comorbidities were present in 25.9% of the group with a history of COVID-19; the most common disease was asthma (5.6%). Allergy history was 4.3% in the group with COVID-19 and 7.8% in the other group (p=0.070). The incidence of post-vaccine adverse events (62.9%) was higher in those with a history of COVID-19 than in those without (57.1%). The most common adverse event was a headache, and it was significantly higher in the group who had COVID-19 compared to those who had not (36.6% vs. 27.7%; p=0.01). Conclusion: In our study, we observed that the rates of undesirable effects after vaccination were high in individuals with a history of COVID-19. Although it is thought that this situation may be related to the developing antibody re- sponse rates, the insufficient number of cases and the lack of determination of the antibody response after infection and vaccination are a disadvantage of the study.