Testing CoronaVac, an Inactivated SARS-CoV-2 Vaccine, in Turkey and Chile

CoronaVac, an inactivated whole-virus COVID-19 vaccine, was widely distributed in national campaigns worldwide based on Phase 1 and 2 clinical trial data. In a Phase 3 trial in Turkey, >10,000 participants in two cohorts (healthcare workers and the general community; age range, 18–59) were randomized to receive two doses of vaccine or placebo 28 days apart. Starting 14 days after the second dose (median follow-up, 43 days), 32 and 9 cases of symptomatic SARS-CoV-2 infection occurred in the placebo and vaccine groups, respectively (efficacy, 83%). Six COVID-19 cases were hospitalized, all in the placebo group. The vaccine was generally well tolerated, and 90% of participants had detectable receptor-binding domain–specific antibodies after two doses.

In a study in Chile (where CoronaVac was the predominant vaccine in the national campaign), investigators assessed the vaccine's effectiveness at preventing COVID-19 and its sequelae. In a prospective observational cohort including 80% of the Chilean population, all persons aged ≥16 were enrolled and categorized by receipt of one, two, or no doses vaccine. From February to May of 2021 among those who received two doses, CoronaVac's preventive effectiveness was 66% (COVID-19), 88% (hospitalization), 90% (intensive care unit admission), and 86% (death); all percentages were somewhat higher among those who sought SARS-CoV-2 testing.