Confusion over efficacy of Chinese vaccines
Gao Fu, head of the Chinese Center for Disease Control and Prevention, attracted a lot of attention when he told a conference in Chengdu that Chinese vaccines "do not achieve very high protection rates."
But shortly after he qualified his statement. His aim, Fu said, was to discuss ways of increasing the effectiveness of the vaccines even further, for example by administering different preparations. He had therefore set out a corresponding "scientific vision," he told the Chinese newspaper the Global Times.
Fu's argument is consistent with what is known about the efficacy of the four vaccines approved in China so far. Indeed, they are by no means ineffective.
Three inactivated vaccines, one vector vaccine
Three of the vaccines — two from Sinopharm and one from Sinovac — are inactivated virus vaccines. They are therefore based on a long-established technology used in vaccines for diseases like hepatitis B or influenza.
Although these COVID-19 vaccines do not achieve efficacy levels as high as those seen in the mRNA vaccines from BioNTech/Pfizer or Moderna, which have over 95% efficacy, they are still significantly more effective than some influenza vaccines, some of which only achieve efficacy levels of 30-60%.
Sinopharm's Vero vaccine, for example, still achieved 79% efficacy in a Phase III study conducted in 10 countries. In a separate study, the United Arab Emirates achieved 86% efficacy.
The efficacy of Sinovac's CoronaVac vaccine ranges from 50-78%, according to preliminary studies from Brazil and Indonesia.
CanSino's fourth Chinese vaccine is a vector vaccine based on an adenovirus type 5, making it comparable in mode of action to AstraZeneca's vaccine. It is expected to achieve an efficacy of 65%.
In principle, the efficacy values improve even further to over 80% when only severe courses of disease are taken into account, namely those that also require hospitalization.
Combination of vaccines not unusual
The idea of combining vaccines to increase efficacy is not fundamentally new. Scientists are currently discussing similar approaches for AstraZeneca's vector vaccine.
And the Russian vaccine Sputnik V also consists, strictly speaking, of two vaccinations with different vector vaccines based on different adenoviruses. The developers hope that this will lead to greater efficacy.
China is practically unable to test the efficacy of its vaccines in its own country because very few cases of infection occur as a result of the strict lockdown measures. Research is therefore dependent on studies conducted in heavily affected countries such as Brazil.