SARS-CoV-2 Seropositivity Level in a Cohort of Turkish Health Care Professionals After COVID-19 Vaccine (CoronaVac) and Assessment of Factors Affecting the Antibody Response

ABSTRACT

Introduction: Although Phase III trial results of many COVID-19 vaccines were reported, the literature regarding community results is inadequate for Corona Vac. This study aims to evaluate the experience gained during the vaccination process among health care workers (HCWs), the measured antibody responses and the factors affecting the response. These findings will contribute to the literature in this field. Materials and Methods: Anti-SARS-CoV-2 (anti-spike) antibodies were measured by ELISA in blood samples taken at least 28 days (28-32) after the second CoronaVac among 264 HCWs vaccinated twice with an interval of 28 days. Information from individuals was collected with an online participation form. Results: A total of 264 HCWs (166 females (63%), 98 males (37%) whose ages werebetween 23-69 (mean 44.22 +/- 11.58) were included independent of their COVID-19 history in the study. After vaccination, 2211CWs (8.3%) were unresponsive, 25 (9.5%) HCWs among responders had a weak antibody response, and 217 (82.2%) had afull antibody response according to the test kit manufacturer. For HCWs with and without a COVID-19 infection history, the full antibody response rates were 91.7% and 77.5%, respectively. The antibody titres tended to be lower in HCWs with no prior COVID-19 infection (p= 0.046). In our study, antibody response was found to be significantly lower in males (p= 0.043). There was a significant decrease in antibody response with advancing age (p= 0.002 Chi-square test, p= 0.030 Spearman coefficient), and the difference was highly significant (p= 0.017) above the age of 60. Conclusion: In this study, it was determined that 91.7% of healthcare workers (weak in 9.5% and full in 82.2%) developed anti-spike antibodies with CoronaVac. It was determined that the factors affecting the development of antibodies were gender, age, and the state of having COVID-19.