MAINLAND APPROVES TRIALS OF NEW HOME-GROWN VACCINE
MRNA booster may widen options for inoculation campaign dependent so far on inactivated shots
The mainland has approved trials for the use of a domestically developed mRNA Covid-19 vaccine as a booster shot – a development that could widen the options for the country’s inoculation campaign.
The Ministry of Science and Technology said it had approved clinical trials on the efficacy and safety of using the vaccine, which used advanced genetic techniques to trigger an immune response, on adults who had already been given shots made using inactivated material from the coronavirus.
The vaccine, ARCoVax, was jointly developed by the Academy of Military Medical Sciences, Suzhou Abogen Biosciences and
Walvax Biotechnology. It is being tested in global multi-site finalstage human trials, which hope to recruit about 30,000 participants. Trial participants in Mexico were inoculated in September, while those in Malaysia were given the shots last month.
The initial phase of China’s vaccination programme relied heavily on inactivated vaccines, but trials are now being carried out to see whether vaccines made using newer techniques can boost immunity.
A non-peer reviewed study published in September on the preprint server medRxiv.org found that a CanSino vaccine made using a vector virus as a booster was significantly more immunogenic than an inactivated vaccine.
Stemirna Therapeutics, a Shanghai-based company, has also registered for trials to compare the antibodies generated by its mRNA vaccine when used as a booster with inactivated vaccines.
The mainland has so far only allowed Covid-19 immunisation using the same technology as the initial shots. It has only approved the use of inactivated vaccines made by Sinopharm and Sinovac, and a vector vaccine made by CanSino Biologics as boosters.
Wang Huaqing, chief expert on immunisation programmes at the Chinese Centre for Disease Control and Prevention, told reporters that these vaccines had been approved because the country had accumulated some data in the early stages of the pandemic, but authorities would have to consider other factors such as vaccine supplies when it came to booster doses.
Mixing vaccines is believed in principle to generate better immune responses. Zeng Guang, a former chief epidemiologist at the centre, told a forum in Shanghai last week that using the same technology to deliver booster shots would be safer and more widely accepted by the public.
But he added: “We can see from data in countries such as Turkey, Thailand and Lebanon … that the real world data showed that using mRNA vaccines or recombinant protein vaccines as a booster dose for inactivated vaccines will achieve better results.”
In countries such as the United Arab Emirates, Brazil and Indonesia, those who were inoculated with Chinese inactivated vaccines have been given the option of taking an mRNA vaccine as a booster.
Walvax has registered for latestage human trials involving 2,000 participants in Yunnan and Guangxi provinces and last month completed a production facility in Yunnan that can produce 200 million doses of mRNA and vectored vaccines a year. Abogen’s plant in Suzhou, which can produce an estimated 40 million doses a year, was granted a licence to produce mRNA vaccines earlier this month.
Using mRNA vaccines … as a booster dose for inactivated vaccines will achieve better results
ZENG GUANG, EPIDEMIOLOGIST