Boxes of Sinovac Biotech’s CoronaVac SARS-CoV-2 vaccine will be displayed at a media event in Beijing, China, on Thursday, September 24, 2020.
Nicolas Bock | Bloomberg | Getty Images
China’s Sinovac Biotech on Wednesday defended the safety and efficacy of its experimental Covid-19 vaccine, after researchers in Brazil released late-stage clinical data that showed efficacy was much lower than initially announced.
The vaccine was only 50.4% effective at preventing symptomatic infections in the Brazilian trial, including data on “very mild” cases, researchers said Tuesday.
Last week, they said the vaccine, called CoronaVac, was 78% effective against “mild to severe” cases.
The news prompted Malaysia and Singapore, which have purchase agreements with Sinovac, to say on Wednesday that they would seek more data from the Chinese company on employment rates before approving and buying goods.
“The results of this phase III clinical trial are sufficient to prove that the safety and effectiveness of the CoronaVac vaccine is good around the world,” said Yin Weidong, chairman of Sinovac Biotech, at a news conference.
Different countries used vaccines from the same batch in their trials, but the countries don’t have identical testing protocols, he said.
Piece-by-piece revelations from Sinovac’s trials and those of studies on other Chinese vaccines have raised concerns that they are not being subject to the same public scrutiny as US and European alternatives.
The data from Brazil was released as Indonesia continued its vaccination campaign, with President Joko Widodo being the first to be vaccinated with Sinovac’s CoronaVac.
Malaysia said on Wednesday that it would only proceed with procurement if the vaccine met the safety and efficacy standards set by local regulators.
On Tuesday, Pharmaniaga Bhd in Malaysia signed a deal with Sinovac to purchase 14 million doses of CoronaVac and later produce it domestically.
Singapore, the only high-income country with which Sinovac has struck a deal, said it would go through official data when Sinovac releases it, rather than rely on the efficacy reported so far, and then decide whether to agree.
Thailand, which has ordered 2 million doses of CoronaVac, said it is still on track to receive and administer the vaccine starting next month, but added that it would request information directly from Sinovac.