CoronaVac vaccine has an overall effectiveness of 50.38%


The CoronaVac vaccine showed a general effectiveness against the new coronavirus of 50.38% in tests carried out with volunteers in Brazil. Data on the rate of the immunizer were released on Tuesday (12) by the Butantan Institute.

This index, also called global efficacy, shows the vaccine’s protective capacity in all cases of covid-19, whether mild, moderate or severe. It is calculated at the end of phase 3 of the clinical trial, comparing the proportion of cases between vaccinated participants and those who received placebo.

According to the criteria of the National Health Surveillance Agency (Anvisa), the incidence rate of the disease among those immunized needs to be less than half the rate presented in the unvaccinated group. If the index is half that presented in placebo-treated, the vaccine is then considered 50% effective, a minimum recommended by the World Health Organization (WHO).

According to the director of the Butantan Dimas Covas Institute, the vaccine has “safety, efficacy and all the requirements that justify its emergency use”, already requested to the regulatory agency, whose response time is 10 days.

Previous data

Last Thursday (7), the institute announced a 78% effectiveness of CoronaVac for mild cases of the disease caused by the new coronavirus and 100% for cases considered moderate and severe, causing some confusion regarding today’s announcement .

The difference to the previous disclosure is that the overall efficiency rate also includes test volunteers with an even milder frame of covid-19, who do not require medical intervention, in the calculation. The previous data refer to more serious cases.

Data from the clinical trial in Brazil differ from those presented in other countries in which the Sinovac vaccine was also tested. In Turkey, for example, the initial analysis found 91% effective, while in Indonesia the rate was 65.3%.


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