The effectiveness of China’s coronavirus vaccines is low and the government is considering mixing them to give them a boost, the country’s top disease control official has said.
Chinese vaccines “don’t have very high protection rates”, said Gao Fu, director of the China Centres for Disease Control, in a rare admission at a conference in the south-western city of Chengdu on Saturday.
Beijing has distributed hundreds of millions of doses in other countries while also trying to promote doubt about the effectiveness of Western vaccines.
“It’s now under formal consideration whether we should use different vaccines from different technical lines for the immunisation process,” Mr Gao said.
Officials at a news conference on Sunday did not respond directly to questions about Mr Gao’s comment or possible changes in official plans, but another CDC official said developers are working on mRNA-based vaccines.
“The mRNA vaccines developed in our country have also entered the clinical trial stage,” said Wang Huaqing. He gave no timeline for possible use.
Experts say mixing vaccines, or sequential immunisation, might boost effectiveness. Researchers in Britain are studying a possible combination of the Pfizer/BioNTech and Oxford/AstraZeneca vaccines.
The coronavirus pandemic, which began in central China in late 2019, marks the first time the Chinese drug industry has played a role in responding to a global health emergency.
Vaccines made by two state-owned drugs firms, Sinovac and Sinopharm, have been exported to 22 countries including Mexico, Turkey, Indonesia, Hungary, Brazil and Turkey, according to the foreign ministry.
The effectiveness of the 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. By comparison, the Pfizer/BioNTech vaccine has been found to be 97% effective.
Health experts say Chinese vaccines are unlikely to be sold to the United States, Western Europe and Japan due to the complexity of the approval process.
Sinovac spokesman Liu Peicheng acknowledged that varying levels of effectiveness have been found but said that can be due to the age of people in a study, the strain of virus and other factors.
Beijing has yet to approve any foreign vaccines for use in China.
Mr Gao gave no details of possible changes in strategy but cited mRNA as a possibility.
“Everyone should consider the benefits mRNA vaccines can bring for humanity,” he said. “We must follow it carefully and not ignore it just because we already have several types of vaccines already.”
He has previously questioned the safety of mRNA vaccines – he was quoted by the official Xinhua News Agency as saying in December that he could not rule out negative side-effects because they were being used on healthy people for the first time.
Chinese state media and popular health and science blogs also have questioned the safety and effectiveness of the Pfizer/BioNTech vaccine.
As of April 2, some 34 million people in China had received both of the required doses of Chinese vaccines and about 65 million had received one, according to Mr Gao.
Sinovac’s Mr Liu said studies had found 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.
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