In a rare admission of the weakness of Chinese coronavirus vaccines, the country’s top disease control official says their effectiveness is low and the government is considering mixing them to get a boost.
Chinese vaccines "don’t have very high protection rates," said the director of the Chinese Center for Disease Control, Gao Fu, at a conference Saturday in the southwestern city of Chengdu.
Beijing has distributed hundreds of millions of doses abroad while trying to promote doubt about the effectiveness of the Pfizer-BioNTech vaccine, which is made using the previously experimental messenger RNA, or mRNA, process.
"It’s now under formal consideration whether we should use different vaccines from different technical lines for the immunisation process," Gao said.
Officials at a news conference Sunday didn’t respond directly to questions about Gao’s comment or possible changes in official plans. But another CDC official said developers are working on mRNA-based vaccines.
Experts say mixing vaccines, or sequential immunisation might boost effectiveness. Researchers in Britain are studying a possible combination of Pfizer-BioNTech and the traditional AstraZeneca vaccine.
The effectiveness of a Sinovac vaccine at preventing symptomatic infections was found to be as low as 50.4% by researchers in Brazil, near the 50% threshold at which health experts say a vaccine is useful. The Pfizer-BioNTech vaccine has been found to be 97% effective.
A Sinovac spokesman, Liu Peicheng, acknowledged varying levels of effectiveness have been found but said that can be due to the age of people in a study, the strain of the virus and other factors.
Liu Peicheng added studies find protection "may be better” if the time between vaccinations is longer than the current 14 days but gave no indication that might be made standard practice.
China has administered 164.4 million doses of its vaccine domestically, according to Our World In Data. Its two state-owned drug-makers, Sinovac and Sinopharm, have exported doses to 22 countries including Mexico, Turkey, Indonesia, Hungary, Brazil and Turkey, according to the foreign ministry.
Hungary is the only European Union member state to have rolled out the Chinese vaccine with Prime Minister Viktor Orban choosing to be inoculated with it.
Chinese authorities have not submitted their vaccines to the European Medicines Agency (EMA) for use across the 27-country bloc.
The EMA has so far approved the use of four vaccines — by Pfizer/BioNTech, AstraZeneca/Oxford University, Moderna, and Johnson & Johnson. It is also currently reviewing Russia's Sputnik V.