Frequency And Factors Associated With Adverse Reactions After Administration of Inactivated COVID-19 Vaccine Among Health Workers.

Background: The 2019 coronavirus (COVID-19) has precipitated a significant public health crisis. Our study aimed to evaluate the prevalence and risk factors associated with adverse reactions to the inactivated CoronaVac vaccine.

Methods: The study involved voluntary health workers who received CoronaVac vaccine. We documented the sociodemographic information of 2,019 participants who volunteered for our study. Of these, 1,964 and 1,702 participants were interviewed by phone 1 month after the first and second dose, respectively, during which they were queried about any adverse reactions.

Results: Within the first week after the first dose, adverse reactions were observed in 856 (43.3%) participants, with 133 (6.7%) experiencing them during the second week, and 96 (4.9%) people at the end of the first month. For the second dose, 276 individuals (16.2%) reported adverse reactions. The prevalence of both local and systemic adverse events ranged from 9.5-11.2% overall. Fatigue was the most common adverse reaction overall, while pain at the injection site was the most frequent local adverse reaction.

Conclusions: The evaluation of both systemic and local side effects revealed no significant adverse reactions to the inactivated CoronaVac vaccine (Sinovac Life Sciences, Beijing, China). Our study found that the incidence of systemic and local adverse responses to the CoronaVac vaccination was lower than the rates reported in studies involving the recombinant adenovirus type-5, BNT162b1, and ChAdOx1nCoV-19 COVID-19 vaccines, all of which underwent the World Health Organization LULUC/PQ evaluation process.