Brazilian researchers testing China’s Sinovac vaccine said on Tuesday that full data showed it was 50.38% effective against Covid-19 in the late stages, almost 30 percentage points lower than previously announced as it increased concerns about the transparency of the study.
The Sao Paulo-based institute in Bhutan said last week that end-stage trials have shown that the CoronaVac vaccine is between 78% and 100% effective, offering complete protection against severe cases of the disease.
After growing pressure from scientists, some of whom accused the organizers of the trial of misleading the public, Butantan said the rates included only volunteers who suffered mild to severe cases of Covid-19. Taking into account data from all volunteers, including those who fell ill with “very mild”
Although it has one of the lowest efficacy levels 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, experts said. in public health.
However, the separate and unorthodox announcement of the efficacy of CoronaVac, which was due to be announced for the first time last month, risks damaging the reliability of the vaccine, which many Brazilians are no longer willing to accept, doctors said.