Waning effectiveness of CoronaVac in real life: A retrospective cohort study in health care workers

CAN G., ACAR H. C. , Aydin S. N. , BALKAN İ. İ. , KARAALİ R., BUDAK B., ...More

VACCINE, vol.40, no.18, pp.2574-2579, 2022 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 40 Issue: 18
  • Publication Date: 2022
  • Doi Number: 10.1016/j.vaccine.2022.03.032
  • Title of Journal : VACCINE
  • Page Numbers: pp.2574-2579
  • Keywords: Inactivated vaccine, COVID-19 vaccine, Health care workers, Vaccine effectiveness


Background: Real-world studies showed varying levels of effectiveness of CoronaVac vaccine against COVID-19 disease. This study aimed to assess the association between the vaccination with CoronaVac and the COVID-19 infections among the health care workers in a university hospital and to determine the vaccine effectiveness against COVID-19 in a period when alpha variant was dominant.Methods: This retrospective cohort study was conducted in a university hospital in Istanbul, Turkey employs 4067 health care workers. The follow-up period was defined as starting 14 days after receiving the second dose for fully vaccinated group. Health care workers were censored when have a positive PCR test result or at the end of the study. Unvaccinated health care workers were censored if they receive any COVID-19 vaccine doses. The incidence rate ratio and Cox regression were used to estimate the unadjusted and adjusted effectiveness of the vaccine.