In a recent study, researchers at the University of Cambridge's Medical Research Council (MRC) Toxicology Unit have uncovered a glitch in mRNA Covid vaccines that triggers an unintended immune response in some individuals. The study found that more than a quarter of people injected with mRNA Covid jabs experienced this immune response, resulting from a malfunction in the way the vaccine is read by the body.

The mRNA vaccines developed by Moderna and Pfizer utilize a strand of genetic material to instruct the body to produce a specific protein that mimics the coronavirus spike and prompts antibody production. This groundbreaking technology, recognized with the Nobel Prize for Medicine in 2023, overcame the previous challenge of the body attacking foreign RNA invaders.

The breakthrough involved replacing one of the RNA bases, uridine, with a synthetic alternative that closely resembles it. This modification allowed for the creation of proteins in the body without triggering an immune response.

However, the recent research from Cambridge has shown that when the body reads this partially synthetic code, the protein-making process encounters difficulties with the uridine analogues. As a result, a nonsensical and harmless protein is produced, which the immune system recognizes and responds to, causing an immune system flare-up. The study, published in Nature, estimated that this occurred in approximately 25-30% of vaccinated individuals.

Despite this glitch, the Cambridge scientists assert that the Covid vaccines still provide strong protection against the coronavirus. The frameshifting issue, which leads to the production of the nonsensical protein, does not affect the intended vaccine response. However, the researchers caution that future mRNA vaccines used for other diseases or infections could potentially lead to the production of viable proteins that are active in the body, posing a possible concern.

Nevertheless, there is no evidence of this occurring in the current Covid vaccines, and the researchers stress that any such issues would be detected in early stages during trials of other mRNA therapeutics.

Dr. James Thaventhiran, senior author of the report, emphasizes the safety of mRNA vaccination against Covid-19, highlighting the billions of doses delivered worldwide by Moderna and Pfizer vaccines, which have saved numerous lives.

The authors of the study propose an effective solution to prevent frameshifting events by modifying the mRNA code to minimize the use of the problematic pseudo-uridine. These findings were shared with the medicines regulator MHRA approximately a year ago, and updated vaccines incorporating the improved form of mRNA are already being developed for cancer treatments and other therapeutics.

Professor Anne Willis, co-senior study author and director of the MRC Toxicology Unit, expresses optimism about the technology, calling it revolutionary as a new medicine platform. She acknowledges the decoding issues associated with mRNA vaccines but emphasizes the safety and efficacy of the Covid vaccines. Furthermore, the discovery of a solution to the glitch greatly minimizes risks associated with this platform for future use.

The research conducted by Cambridge scientists serves as a valuable contribution to the ongoing efforts in understanding and improving mRNA technology, ensuring the development of safer and more effective vaccines and therapeutics in the future.