Chinese state media has rushed to defend its locally developed coronavirus vaccines, with a senior health official insisting that he was “misunderstood” when he appeared to question the jabs’ efficacy.
Gao Fu, head of the Chinese Center for Disease Control and Prevention, told a conference over the weekend that the government was considering mixing vaccines and varying dosing regimens as a way to deal with “not high efficacy” of existing jabs. It was a rare official acknowledgment of difficulties facing China’s vaccination programme.
But on Sunday, Gao said that his remarks had been “taken out of context” and misunderstood.
“After talking about different immunisation strategies, I mentioned the issue of vaccine protection rates and expressed my reflection that we can optimise our administration process,” he told Guancha.com, a Chinese media outlet.
Chinese vaccines, which Beijing has pledged to supply to dozens of countries, have been criticised for their varying efficacy rates. Some only just pass the World Health Organization threshold of 50 per cent efficacy, while developers have been slow to release phase 3 trial data.
China’s leading jabs, one from Sinovac, a private company, and two from state-run Sinopharm, use well-established technology that injects a chemically inactivated whole virus to elicit an immune response. But studies suggest that their efficacy is below that of mRNA vaccines such as those developed by Moderna or BioNTech/Pfizer.
Chile has defended its decision to rely heavily on Sinovac’s vaccine even as the country battles a resurgence of the virus, despite one of the highest per capita vaccination rates in the world.
Andrés Couve Correa, Chile’s science minister, said on Twitter on Sunday that Sinovac had helped prevent hospitalisations for moderate and severe cases.
The Global Times, a state-run publication, denied that Sinovac’s efficacy rates were to blame for infections in Chile. A study by the University of Chile, which found that effectiveness after the first of two shots for CoronaVac was only 3 per cent, is based on “very limited” data, the newspaper quoted an unnamed source as saying.
But Jin Dong-yan, a virologist at the University of Hong Kong, said on Monday that Chinese vaccines’ efficacy rates were among the lowest in the world.
“Chinese vaccines can provide a certain level of protection, especially for reducing severe disease and deaths, but it’s hard to reach herd immunity,” he said. “Even if everyone in China takes the vaccines, it can only slow down the spread.”
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China’s defence of its vaccines coincided with the publication of long-awaited phase 3 trial results and analysis from Sinovac’s Brazilian partners. It marked the first time a detailed breakdown of phase 3 trial data from a Chinese vaccine had been made public.
The data, which is yet to be peer-reviewed by independent scientists, is in line with estimations of the vaccine’s performance, with an overall efficacy rate of 50.7 per cent, just above the WHO-recommended cut off.
The researchers explained that the relatively low rate was due to the conditions of the study, which was conducted among health workers. “The case definition and professional profile of the study population allowed highly sensitive surveillance and the study was able to detect even the mildest cases of Covid-19,” they said.
The researchers added that the vaccine was “highly protective” against moderate and severe Covid-19 and that its efficacy rate climbed to 62.3 per cent if there was an interval of more than 21 days between doses.
Additional reporting by Wang Xueqiao