Covid-19: China’s CoronaVac vaccine offers 83.5% protection against symptomatic infection, interim analysis finds

Griffin, Shaun

The interim analysis, published in the Lancet, showed that during a median follow-up period of 43 days (interquartile range 36 to 48 days), nine cases of symptomatic covid-19, confirmed by polymerase chain reaction testing, were reported in the vaccine group (31.7 cases (14.6 to 59.3) per 1000 person-years) and 32 were reported in the placebo group (192.3 cases (135.7 to 261.1) per 1000 person-years) 14 days or more after the second dose, yielding a vaccine efficacy of 83.5% (95% confidence interval 65.4% to 92.1%;P<0.0001). Lead author Murat Akova, from Hacettepe University Medical School in Turkey, said, “In order to bring the covid-19 pandemic under control, the world needs every single dose of safe and effective vaccines, and our results add important evidence of the safety and effectiveness of inactivated virus vaccines. Noting that the World Health Organization had given emergency use approval to another inactivated vaccine from a different Chinese producer (Sinopharm-Beijing), the authors added, “Our results add to the existing evidence on safety and efficacy of inactivated vaccines for prevention of covid-19.”