The researchers found that the efficacy of a vaccine against the Sinovac coronavirus was only 50.4%.
In a rare admission that China’s coronavirus vaccines are weak, the country’s top disease control official said their effectiveness is low and the government is considering mixing them up to give them a boost.
Chinese vaccines “do not have very high rates of protection,” Chinese Centers for Disease Control director Gao Fu said at a conference in the southwestern city of Chengdu on Saturday.
Beijing has distributed hundreds of millions of doses in other countries.
“It is now under formal review whether we should use different vaccines from different technical lines for the vaccination process,” Gao said.
The rate of effectiveness of a vaccine against the coronavirus of Sinovac, a Chinese developer, in preventing symptomatic infections, was found to be 50.4% by Brazilian researchers. In comparison, the vaccine manufactured by Pfizer-BioNTech was found to be 97% effective.
Beijing has yet to approve any foreign vaccines for use in China, where the coronavirus emerged at the end of 2019.
Gao did not give any details about possible changes in strategy, but mentioned mRNA, a previously experimental technique used by some Western vaccine developers while Chinese drugmakers used traditional technology.
“Everyone should consider the benefits that mRNA vaccines can bring to mankind,” said Gao. “We have to watch it carefully and not ignore it just because we already have several types of vaccines.”
Gao previously raised questions about the safety of mRNA vaccines. It was quoted by the state-run Xinhua News Agency as saying in December that it couldn’t rule out negative side effects because they were first used on healthy people.
Chinese state media and popular health and science blogs have also questioned the safety and efficacy of the Pfizer-BioNTech vaccine, which uses mRNA.
As of April 2, some 34 million people had received the two doses required by Chinese vaccines and about 65 million had received one, according to Gao.
Experts say mixing vaccines, or sequential vaccination, could increase effectiveness rates. Trials around the world are aimed at mixing vaccines or giving a booster shot after a longer period.
British researchers are studying a possible combination of the Pfizer-BioNTech and AstraZeneca vaccines.