Chinese vaccine against Covid-19 is much less effective than that initially presented in Brazil


Brazilian researchers testing the Chinese Sinovac vaccine said on Tuesday comprehensive data showed it was 50.38% effective against Covid-19 in late-stage trials, nearly 30 percentage points lower than previously reported, as concerns grow about the transparency of the study.
The São Paulo-based Butantan Institute said last week that late-stage trials have shown the CoronaVac vaccine to be between 78% and 100% effective, providing full protection against severe cases of the disease.
However, after increasing pressure from scientists, some of whom accused trial organizers of misleading the public, Butantan said those rates only included volunteers who suffered from mild to severe cases of Covid-19. When the data of all volunteers are taken into account, including those who contracted “very mild” cases of Covid-19 and did not require any medical assistance, the total effectiveness rate drops to 50.38%, Butantan said Tuesday.
Although it has one of the lowest efficacy rates for any new coronavirus vaccine, CoronaVac is still more effective than some influenza vaccines and can be kept inexpensively in a regular refrigerator, making it less expensive. makes it a viable option for developing countries, public health experts said.
However, the piecemeal and unorthodox news of CoronaVac’s effectiveness rate, which was originally due to be announced last month, risks damaging the credibility of a vaccine that many Brazilians are already reluctant to take, doctors have said.


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