The tepid results could also be problematic for Chinese officials, given that they had touted the efficacy of the vaccines made by Sinovac and Sinopharm. Even though the vaccines had not received regulatory approval, and data from late-stage trials had not been made public, Beijing gave them to thousands of Chinese people under an emergency use policy; it plans to vaccinate 50 million people by the middle of next month.
State media in China played down the news from Brazil. Global Times, a state-owned nationalist tabloid, ran a headline that said the Sinovac vaccine was “100 percent effective in preventing severe cases, could reduce hospitalizations by 80 percent.”
The new data could heighten skepticism among people around the world who are already wary of Chinese-made vaccines, given that the country has a history of vaccine quality scandals. A study from the Chinese University of Hong Kong found that just 37.2 percent of respondents in Hong Kong were willing to be vaccinated.
Scientists had already raised questions about the piecemeal way in which efficacy data about the Chinese vaccines had been released. Indonesia said on Monday that its interim analysis found CoronaVac to have an efficacy rate of 65.3 percent. Last month, Turkey said it had an efficacy rate of 91.25 percent, but that was based on preliminary results from a small clinical trial.
The vaccine had long taken on a political dimension in Brazil. President Jair Bolsonaro had spoken derisively about CoronaVac, fueling an growing anti-vaccination movement in the country, where more than 200,000 people have died from Covid-19. The vaccine had been championed by São Paulo’s governor, João Doria, who is widely expected to run for president in 2022 and is among Mr. Bolsonaro’s most vocal critics.
In Brazil, officials say the higher efficacy rate previously announced for CoronaVac pertained to the protection it offered against developing Covid-19 symptoms significant enough to require treatment. While officials had asserted last week that the vaccine provided absolute protection against moderate to severe symptoms, they had not disclosed another group who had “very mild” infections despite having been vaccinated.
Denise Garrett, a Brazilian-American epidemiologist and vaccine expert, said there was no reason to doubt CoronaVac’s safety, adding that the data presented so far suggested it would provide a satisfactory level of protection. But Dr. Garrett said the vague and sometimes misleading manner in which information about the vaccine had been made public could shake people’s confidence in its reliability and fuel the political battle over the vaccine.