SÃO PAULO – China’s efforts to bolster its image by delivering Covid-19 vaccines to developing countries suffered a setback after it was discovered that one of its leading vaccine candidates was 50% effective in late-stage studies in Brazil, which is evident was below previous results.
While Sinovac’s CoronaVac efficacy rate still hits the 50% threshold the World Health Organization considers good enough for widespread use, scientists said a lack of transparency about the data could jeopardize a vaccine’s credibility for Brazilians and others around the world hesitate to take.
The Brazilian Butantane Institute, a São Paulo-based public institute that was the first to complete the late studies on the CoronaVac vaccine. had said last week It has been shown to be 78% effective and provide complete protection against severe cases of the disease.
But after increasing pressure from Brazilian scientists, some of whom accused the organizers of the process of misleading the public, Butantan said Tuesday that those rates only included volunteers who had suffered mild to severe cases of Covid-19. When data from all volunteers were taken into account – including those who had “very mild” cases of Covid-19 and didn’t need medical attention – the overall effectiveness rate dropped to 50.4%, butantane said.
Sinovac did not respond to requests for comment.