The boxes of Sinovac Biotech’s CoronaVac SARS-CoV-2 vaccine are on display 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 Covid-19 experimental vaccine after Brazilian researchers released end-stage clinical data showing far lower efficacy than initially announced.
The vaccine was only 50.4% effective in preventing symptomatic infections in the Brazilian trial, including data on “very mild” cases, researchers said Tuesday.
Last week they said the vaccine, called CoronaVac, showed 78% effectiveness against “mild to severe” cases.
The news prompted Malaysia and Singapore, which have purchase agreements with Sinovac, to say on Wednesday that they would ask for more data from the Chinese company on efficiency indices before approving and buying supplies.
“These results of the Phase III clinical trials are sufficient to demonstrate that the safety and efficacy of the CoronaVac vaccine are good worldwide,” Yin Weidong, president of Sinovac Biotech, told a news conference.
Different countries used vaccines from the same batch in their trials, but countries do not have identical testing protocols, he said.
Pieces of Sinovac trials, as well as studies of other Chinese vaccines, have raised concerns that they are not subject to the same public scrutiny as European and American alternatives.
Data from Brazil was released just as Indonesia began its vaccination campaign, with President Joko Widodo being the first to be inoculated with Sinovac’s CoronaVac.
Malaysia said on Wednesday it would continue with the acquisition if the vaccine met the safety and efficacy standards of local regulators.
On Tuesday, Malaysia Pharmaniaga Bhd signed an agreement with Sinovac to buy 14 million doses of CoronaVac and subsequently to manufacture it nationwide.
Singapore, the only high-income country with which Sinovac has reached an agreement, said it would go through the official data when Sinovac released it, rather than relying on the effectiveness reported so far, and then decide whether the would approve.
Thailand, which has ordered 2 million doses of CoronaVac, said it was still on track to receive and administer the vaccine as of next month, but added that it would ask Sinovac for information directly.