CoronaVac SARS-CoV-2 Sinovac Biotech vaccine boxes 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 experimental vaccine Covid-19, after researchers in Brazil released late-stage clinical data showing much lower efficacy than originally announced.
The vaccine was only 50.4% effective in preventing symptomatic infections in the Brazilian study, including data on “very mild” cases, the researchers said on Tuesday.
Last week, they said the vaccine, called CoronaVac, had been shown to be 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 will look for more data from the Chinese company on efficiency rates before approving and buying consumables.
“These results of Phase III clinical trials are sufficient to demonstrate that the safety and efficacy of CoronaVac vaccine are good worldwide,” Sinovac Biotech President Yin Weidong told a news conference.
Different countries used vaccines from the same batch in their studies, but countries do not have identical testing protocols, he said.
Fragmentary disclosures from Sinovac studies, as well as those from other Chinese vaccine studies, have raised concerns that they are not subject to the same public scrutiny as US and European alternatives.
Data from Brazil was released just as Indonesia launched 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 purchase only if the vaccine meets the safety and efficacy standards of local regulators.
On Tuesday, Malaysia Pharmaniaga Bhd signed an agreement with Sinovac to purchase 14 million doses of CoronaVac and subsequently to manufacture it domestically.
Singapore, the only high-income nation with which Sinovac has reached an agreement, said it will go through the official data when Sinovac releases it, rather than depending on the effectiveness reported so far and then decide whether to approve.
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 will ask for information directly from Sinovac.