Brazilian researchers who tested China’s Sinovac vaccine said Tuesday that full data show they are 50.38% effective against Covid-19 in end-stage trials, nearly 30 percentage points lower than previously announced. as concerns about the transparency of the study grow.
The São Paulo-based Butantan Institute said last week that final-stage trials had shown that the CoronaVac vaccine was between 78% and 100% effective, offering total protection against serious cases of the disease. .
However, after increasing pressure from scientists, some of whom accused the organizers of the trial of misleading the public, Butantan said these fees only include volunteers who suffered mild to severe cases of Covid-19. . When considering the data from all volunteers, including those who contracted “very mild” cases of Covid-19 and did not need medical care, the overall effectiveness rate drops to 50.38%, Butantan said Tuesday.
Despite having one of the lowest efficacy rates for any new coronavirus vaccine, CoronaVac is even more effective than some flu vaccines and can be stored cheaply in a regular refrigerator, making it a viable option for developing countries, public health experts said.
However, the slow and unorthodox announcement of CoronaVac’s effectiveness rate, which was first announced last month, runs the risk of damaging the credibility of a vaccine that many Brazilians are already reluctant to take, doctors said.