Two successful US vaccine trials suggest there is a strong possibility that their Chinese counterparts will also prove effective, according to the co-founder of a Chinese drug company.
On Friday Pfizer and BioNTech asked the US Food and Drug Administration to authorise the emergency use of their vaccine after the final clinical trials showed it could offer 95 per cent protection. Their submission came days after Moderna reported a similar efficacy rate - 94.5 per cent - for its vaccine.
"The high efficacy (as a result of) their levels of neutralising antibodies indicates it is not difficult to reach high efficacy.
"It is not difficult for the vaccines developed by Chinese companies ... to reach efficacy of 70 or 80 per cent," said Zhu Tao, co-founder and chief science officer of Chinese vaccine developer CanSino Biologics in an interview on Saturday.
"It looks very promising that all the vaccines we are developing can achieve clinical success."
However, Zhu said it did not necessarily mean all vaccines could achieve an efficacy rate of 90 per cent or more, but they would still be "successful" if they reached the levels required by the country's regulator.
China's Centre for Drug Evaluation has said drugs must be at least 50 per cent effective, and ideally exceed 70 per cent.
Zhu said efficacy rates were not the only benchmarks, because other factors such as safety and convenience would also determine how effective the drugs would prove in reality.
Zhu also said that published data showed that CanSino's candidate vaccine, which uses a common flu virus as a vector for genetic material from the coronavirus, had seen fewer adverse responses than a similar product developed by Oxford University and AstraZeneca, which used a virus found in chimpanzees.
Another possible advantage the firm's vaccine has is that it remains stable at temperatures of between 2C and 8C (36-46F) for 24 months, making storage and handling easier in comparison with products such as those produced by Pfizer and Moderna that need to be kept at lower temperatures.
China has 12 vaccine candidates under clinical trials. CanSino's Ad5-nCoV vaccine, which was jointly developed by the Chinese military, is currently undergoing late-stage trials involving more than 40,000 volunteers in countries including Pakistan, Russia and Mexico.
Mexico said earlier this month it would purchase 35 million CanSino vaccine doses for its citizens.
Zhu also said the company needed to see 50 cases of Covid-19 among trial volunteers to pass a statistical threshold known as the interim endpoint before it can review how effective the vaccine is.
"The case number is increasing but we don't know whether we can reach the interim endpoint by the end of this year. It's definitely easier to collect cases in the US," Zhu said, referring to the higher number of cases in America.
The company's candidate vaccine has been found to induce an immune response with a single dose, but it is also testing a two-dose regime. It is also carrying out separate trials to test immunity after six months and the vaccine's effect on children and over-65s.
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