China has joined the race to build a better Covid-19 vaccine using engineered circular RNA, a form of biotechnology that scientists hope can lead to cheaper and more effective shots. A group of scientists from Peking University, the Chinese Academy of Medical Sciences and Peking Union Medical College in Beijing have been testing a circular RNA (circRNA) vaccine candidate targeting the tip of the coronavirus’s spike protein, which the virus uses to dock with the body’s receptors and cause infection. The team have released a preprint paper of the results of laboratory tests and animal trials and the study is being reviewed by scientific journal Cell. Companies and scientists are exploring the vaccine potential in transforming linear RNA into a circular shape. The change would make it more difficult for the body to break down enzymes, allowing them, in theory, to last longer and induce more durable and stronger immune responses. If successful, the circular RNA technology could have much wider applications and possibly be used to develop therapies for cancer and genetic diseases. In their paper, the Chinese scientists said their circRNA vaccine elicited stronger neutralising antibodies and T-cell responses and robust protection against Sars-CoV-2 in both mice and rhesus macaques than an mRNA vaccine that they used for comparison. They did not specify the mRNA vaccine used in the trials but said it was neither the one developed by Pfizer/BioNTech nor Moderna. Will the coronavirus continue to evolve after Omicron? The Chinese scientists also found that in animal trials, their candidate targeting the Delta variant could protect the animals from both the Delta and Omicron variants. However, the candidate targeting Omicron could only protect the animals against Omicron, but not the Delta variant. But it is not known how well the vaccine candidate can induce an immune response from humans, nor how safe it is. The scientists said they did not detect any adverse effects in the animals. The circRNA vaccine was also more stable and even after two weeks stored at room temperature, could still express the antigen well, the team said. That suggested the potential for circRNA vaccines to be stored at higher temperatures than the existing mRNA vaccines, which must be kept at minus 20 degrees Celsius (minus 4 Fahrenheit) to minus 70 degrees Celsius. US start-up Orna Therapeutics is looking at ways to use circular RNA technology to develop therapeutics for cancer, autoimmune diseases, and genetic disorders. One of the founders of Moderna, venture capital firm Flagship Pioneering, also launched a start-up called Laronde in May last year with US$50 million in capital to develop circular RNA therapy. On the vaccine front, a team from Singapore’s Genome Institute of Singapore and Institute of Bioengineering and Bioimaging, together with the National University of Singapore Yong Loo Lin School of Medicine, was awarded a contract by the Wellcome Trust in January this year to manufacture circular RNA for mRNA vaccines. The Singapore team hopes the circRNA vaccines will require smaller doses and be cheaper to manufacture. However, so far none of the vaccine or therapeutic candidates using the technology has been tested on humans.
