Effectiveness of CoronaVac vaccination against COVID-19 development in healthcare workers: real-life data.

This study was designed to investigate the effectiveness of CoronaVac in preventing COVID-19 in healthcare workers (HCWs) during the alpha variant-dominant period. A total of 1911 HCWs were included. While COVID-19 developed in 4.1% of double-dose vaccinated HCWs and 11.27% of unvaccinated HCWs, the effectiveness of CoronaVac in preventing the development of COVID-19 was 65%. Compared with the results of a previous trial in Turkey, a lower effectiveness of CoronaVac against COVID-19 was detected in this real-life study. This finding suggests that mass vaccination and booster doses are needed.