Brazilian researchers who tested China’s Sinovac Vaccine said on Tuesday that full data shows it is 50.38% effective against Covid-19 in late-phase studies, nearly 30 percentage points lower than previously announced, amid concerns about the study’s transparency. increase.
The São Paulo-based Butantan Institute said last week that late-stage studies showed that the CoronaVac vaccine is between 78% and 100% effective and provides total protection against severe cases of the disease.
However, after mounting pressure from scientists, some of whom accused the organizers of the trial of misleading the public, Butantan said those numbers only pertained to volunteers suffering from mild to severe cases of Covid-19. When the data from all volunteers is taken into account, including those who contracted “very mild” cases of Covid-19 and did not require medical attention, the overall efficacy drops to 50.38%, Butantan said Tuesday.
Despite having one of the lowest efficacy rates for any new coronavirus vaccine, CoronaVac is still 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 patchy and unorthodox announcement of CoronaVac’s efficacy, first announced last month, threatens to hurt the credibility of a vaccine that many Brazilians are already reluctant to hurt, doctors said.