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Background: COVID-19 (Coronavirus disease 2019) is a global pandemic that affected more than 125 million people all over the world. Vaccines will play a key role in the control of this pandemic. Although inactive vaccine technologies are reliable and being used for a long time, Coronavac is a newly developed vaccine and studies on the side effects of this vaccine are limited.
Aims: The aims of this study is to evaluate the frequency of possible side effects of Coronovac vaccine and to investigate whether there is a difference between the 1st and 2nd dose vaccines in terms of the frequency of side effects.
Study Design: This single-center, retrospective descriptive study was carried out in health care workers (HCWs) of Gazi University Hospital who received 2 doses of Coronavac vaccine between January and March 2021. At least 14 days after 2 dose of vaccination, serious advers events, non-serious advers events and possible side effects are collected by the questionnaire forms prepared for the study by the researchers.
Methods: All data were analyzed by IBM SPSS Statistics version 20.0 (IBM Corp., Armonk, N.Y., USA). The questionnaire forms, prepared for the study, were delivered to volunteer HCWs manually or online by the researchers at least 14 days after 2 dose of vaccination. The data obtained through the questionnaires were transferred to the computing environment and analyzed.
Results: 1102 HCWs were enrolled in the study and 392 (35.6 %) had at least one adverse event after the 1st or 2 nd dose Coronavac vaccine. The most common adverse events were: Headache 230 (20.9%), fatigue 225 (20.4 %) and local reactions 193 (17.5%). Serious adverse events occurred in 3 (0.3 %) patients (1 Anaphylaxis,2 Angioedema) after vaccination. The majority of adverse events associated with Coronavac vaccine occured within the first 48 hours. The incidence of adverse events after vaccination is higher in healthcare workers with a known history of vaccine and non-vaccine allergies (42.7% vs. 34.3%, p<0.05, Chi-square test). More frequent side effects were observed after second doses in healthcare workers who developed side effects after the 1st dose of vaccine (70.5% vs. 5.3, p<0.01, Chi-square test)
Conclusion: In our study, we found that short-term adverse events of Coronovac vaccine were found to be consistent with phase 1/2 studies and it was observed to be safe for clinical use. However, there is still a need for long-term follow-up in terms of monitoring side effects after administration for the safety of vaccine use.
Key words: advers event, Coronavac, healthcare worker, side effect, vaccine