The tepid results can also be problematic for Chinese officials, as they praised the effectiveness of vaccines made by Sinovac and Sinopharm. Although the vaccines have not received regulatory approval and data from final-stage tests has not been released, Beijing has given them to thousands of Chinese under an emergency use policy; plans to vaccinate 50 million people by the middle of next month.
State media in China downplayed news from Brazil. Global Times, a state nationalist tabloid, published a headline that said that the Sinovac vaccine was “100% effective in preventing serious cases, it could reduce hospitalizations by 80%”.
The new data may increase skepticism among people around the world who already fear Chinese vaccines, as the country has a history of vaccine quality scandals. A study by the Chinese University of Hong Kong found that only 37.2% of respondents in Hong Kong were willing to be vaccinated.
Scientists had previously raised questions about the fragmented way in which efficacy data on Chinese vaccines was released. Indonesia said on Monday that its interim analysis found that CoronaVac had an effectiveness rate of 65.3%. Last month, Turkey said it had an effectiveness rate of 91.25 percent, but it was based on preliminary results from a small clinical trial.
The vaccine has long acquired a political dimension in Brazil. President Jair Bolsonaro scorned CoronaVac, fueling a growing anti-vaccination movement in the country, where more than 200,000 people died from Covid-19. The vaccine was defended by the governor of São Paulo, João Doria, who is expected to run for president in 2022 and is among Bolsonaro’s biggest critics.
In Brazil, officials say the highest rate of effectiveness previously announced for CoronaVac concerned the protection it offered against the development of Covid-19 symptoms significant enough to require treatment. Although officials said last week that the vaccine offers absolute protection against moderate to severe symptoms, they did not disclose another group that had “very mild” infections, despite having been vaccinated.
Denise Garrett, a Brazilian-American epidemiologist and vaccine specialist, said there was no reason to doubt the safety of CoronaVac, adding that the data presented so far suggested that it would provide a satisfactory level of protection. But Dr. Garrett said the vague and sometimes misleading way in which information about the vaccine was released could undermine people’s confidence in its reliability and fuel the political battle over the vaccine.