São Paulo – China’s efforts to boost its image by providing Covid-19 vaccines to the developing world suffered a setback after it was found that one of the main candidates for vaccination was 50% effective in last-phase trials in Brazil, far less than previous results showed.

While Sinovac’s CoronaVac Efficacy Rate still meets the 50% threshold that the World Health Organization considers good enough for widespread use, scientists said the lack of transparency around the data threatens to damage the vaccine credibility of Brazilians and others around the world. Are already reluctant to take.

Instituto Boutantan Brasil, a public institute based in Sao Paulo that is the first to complete late-stage trials of the CoronaVac vaccine, He said last week It has a proven 78% effectiveness and provides complete protection against severe cases of the disease.

But after mounting pressure from Brazilian scientists, some of whom accused the trial organizers of misleading the public, Butantan said Tuesday that those rates only include volunteers who have experienced mild to severe cases of Covid-19. Butantan said when the data from all of the volunteers were considered – including those who had „very mild“ cases of Covid-19 and did not need medical help – the overall effectiveness rate dropped to 50.4%.

Sinovac did not respond to requests for comment.