China has yet to approve any mRNA vaccines, which have the highest efficacy rates, despite the recent surge in cases in Shanghai . The authorities have not explained the delay, even though Fosun Pharmaceuticals has a commercial deal to distribute 100 million doses of BioNTech’s vaccine. Experts worry over ‘booster fatigue’ amid hunt for new vaccine improvements Many analysts believe the authorities are waiting for a home-grown mRNA vaccine to be developed . Here is what we know so far about that quest. What are the advantages of an mRNA vaccine? The vaccines – which use messenger RNA to teach the body to generate a protein that will trigger an immune response – have a much higher efficacy rate than ones made using older forms of technology. The first mRNA vaccines produced by Moderna and Pfizer/BioNTech had efficacy rates of above 90 per cent, well above some of the inactivated vaccines produced in China – which use dead matter from the virus to trigger an immune response. How much progress has been made? Some mRNA vaccines are undergoing phase 3 clinical trials while others are “in the review and approval process”, Lei Zhenglong, a National Health Commission official said last month. A vaccine developed by Abogen Biosciences, Walvax Biotechnology and the PLA Academy of Military Science is currently undergoing an extensive trial in China, Mexico and Indonesia. A paper about a phase 1 trial, published in The Lancet Microbe in January, showed it generated twice the level of neutralising antibodies seen in people who had recovered from a Covid-19 infection. One advantage of the vaccine is that it can be kept in a standard refrigerator rather than a deep freeze, which is something other mRNA vaccines need. Another candidate vaccine developed by AIM Vaccine is currently undergoing a phase 2 trial and the maker said it plans to start the final stage in May or June. How does Omicron affect these mRNA vaccine developers? The highly transmissible variant has forced developers around the world to make changes. Shanghai-based Stemirna Therapeutics, which started clinical trials on an mRNA vaccine last year, has now updated its vaccine and is currently conducting a Phase 2 trial in Laos. It targets a unique mutation of the Omicron and Delta variants and the company said it is confident it will offer effective protection against the current dominant variant. Meanwhile Abogen, another Chinese firm, has gained approval to start trials on an updated vaccine in the United Arab Emirates. It says it is in talks with regulators in China and other countries to conduct further trials. Why are some developers who have approved Covid-19 vaccines still jumping on the mRNA bandwagon? CanSino Biologics, which already has an approved vectored Covid-19 vaccine under its belt and has gained approval to start clinical trials on an mRNA vaccine, says the new technology has significant advantages over traditional vaccines. It said the advantages include fast, scalable and uniform production, while the neutralising antibodies its candidate produces work better on different variants. China National Biotec Group, which already had two inactivated vaccines approved, and CSPC Pharmaceutical have also gained approval to start clinical trials on an mRNA vaccine. What’s China’s official stance on mRNA vaccines? Gao Fu, director of the Chinese Centre for Disease Control and Prevention, has been urging the vaccine industry to develop domestic vaccines. Another delay to BioNTech Covid-19 vaccine study in China In a public forum last June, he told vaccine developers that mRNA vaccine development “gave China the opportunity to pass the others in the world vaccine industry”. A five year plan for the bio-economy unveiled by the National Development and Reform Commission also called for more innovative platforms to be built to develop mRNA vaccines.