Chinese state media have rushed to defend their locally developed coronavirus vaccines, with a senior health official insisting he was “misunderstood” when he appeared to question the effectiveness of the injections.
Gao Fu, head of the China Center for Disease Control and Prevention, told a conference this weekend that the government was considering mixing vaccines and varying dosing schedules as a way to deal with “low efficacy” of existing injections. It was a rare official recognition of the difficulties faced by China’s immunization program.
But on Sunday, Gao said his words were “taken out of context” and misunderstood.
“After talking about different vaccination strategies, I brought up the issue of vaccine protection rates and expressed my thoughts on how we can optimize our delivery process,” he told Guancha.com, a Chinese media.
Chinese vaccines, which Beijing has pledged to deliver to dozens of countries, have come under fire for varying rates of effectiveness. Some barely exceed the World Health Organization’s 50% effectiveness threshold, while developers are slow to release data from Phase 3 trials.
The main Chinese jabs, one from Sinovac, a private company, and two from Sinopharm, a state-owned company, use well-established technology that injects a whole chemically inactivated virus to trigger an immune response. But studies suggest that their effectiveness is lower than that of mRNA vaccines such as those developed by Moderna or BioNTech / Pfizer.
Chile has defended its decision to rely heavily on the Sinovac vaccine even as the country fighting a resurgence of the virus, despite one of the highest per capita vaccination rates in the world.
Andrés Couve Correa, Chilean Minister of Science, said on Twitter Sunday that Sinovac had helped prevent hospitalizations for moderate and severe cases.
The Global Times, a state publication, denied that Sinovac’s effectiveness rates were to blame for infections in Chile. A University of Chile study, which found efficacy after the first of two CoronaVac injections was only 3%, is based on “very limited” data, the newspaper said citing an anonymous source. .
But Jin Dong-yan, a virologist at the University of Hong Kong, said Monday that Chinese vaccine efficacy rates were among the lowest in the world.
“Chinese vaccines can provide a certain level of protection, especially to reduce serious illness and death, but herd immunity is difficult to achieve,” he said. “Even if everyone in China takes the vaccines, it can only slow the spread.”
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China’s defense of its vaccines coincided with the publication of results from the long-awaited phase 3 trials and analyzes from Sinovac’s Brazilian partners. It was the first time that a detailed breakdown of phase 3 trial data for a Chinese vaccine had been made public.
The data, which has not yet been reviewed by independent scientists, is consistent with estimates of vaccine performance, with an overall efficacy rate of 50.7%, just above the threshold recommended by the WHO .
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 the occupational profile of the study population allowed for very 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 effectiveness rate jumped to 62.3% if there was an interval of more than 21 days between doses.
Additional reporting by Wang Xueqiao
