Boxes of Sinovac Biotech’s CoronaVac SARS-CoV-2 vaccine are displayed at a media event in Beijing, China on Thursday, September 24, 2020.
Nicolas Bock | Bloomberg | Getty Images
China’s Sinovac Biotech defended the safety and efficacy of its experimental Covid-19 vaccine on Wednesday, after researchers in Brazil released late-stage clinical data showing much less effectiveness than initially announced.
The vaccine was only 50.4% effective in preventing symptomatic infections in the Brazilian trial, including data on “very mild” cases, the researchers said on 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 purchasing agreements with Sinovac, to say on Wednesday that they would seek more data from the Chinese company on efficacy rates before approving and buying supplies.
“The results of the Phase III clinical trials are sufficient to prove that the safety and efficacy of the CoronaVac vaccine are good worldwide,” Sinovac Biotech President Yin Weidong told a news conference.
Different countries have used vaccines from the same batch in their tests, but countries do not have identical testing protocols, he said.
Gradual disclosures of Sinovac’s tests, as well as studies of other Chinese vaccines, have raised concerns that they are not subject to the same public scrutiny as American and European alternatives.
The data from Brazil were released at the moment when Indonesia was launching its vaccination campaign, with President Joko Widodo being the first to be vaccinated with Sinovac’s CoronaVac.
Malaysia said on Wednesday that it will only proceed with the purchase if the vaccine meets the safety and efficacy standards of local regulators.
On Tuesday, Pharmaniaga Bhd of Malaysia signed an agreement with Sinovac to buy 14 million doses of CoronaVac and later manufacture it domestically.
Singapore, the only high-income country with which Sinovac struck a deal, said it would go through official data when Sinovac released it, rather than relying on the effectiveness reported so far, to then decide whether to approve it.
Thailand, which has ordered 2 million doses of CoronaVac, said it was still in the process of receiving and administering the vaccine as of next month, but added that it would ask for information directly from Sinovac.