Results
We enrolled 1582 HCWs. At enrolment, 1040 (66%) had received two doses
of CoronaVac; 421 (27%) were unvaccinated. During the study period, 72
PCR-positive SARS-CoV-2 infections occurred; 36/39 (92%) sequenced
samples were classified as delta variant. The adjusted primary series VE
against COVID-19 illness was 29% (95% CI:-51%;67%). For the
delta-predominant period, adjusted primary series VE was 19% (95%
CI:-81%;64%). For the entire analysis period, adjusted primary series
VE was 39% (95% CI:-40%;73%) for HCW vaccinated within 14–149 days,
and 19% (95%CI:-81;63) for those vaccinated ≥150 days.