'Error' discovered in Moderna, Pfizer Covid vaccines: What does science say?

A new discovery of a "flaw" in mRNA technology in the Moderna and Pfizer COVID-19 vaccines has scientists reconsidering the vaccine's design.

When researchers at the University of Cambridge (UK) delved into mRNA technology, hoping to improve mRNA therapy in the future, they discovered that the technology was "faulty", causing some to feel concerned about "off-target effects".

Does the "faulty" mRNA vaccine affect the vaccinated person?

New research has identified chemical changes in some mRNA molecules found in the Moderna and Pfizer vaccines that cause the mRNA sequence to 'slip' as it is decoded in cells.

New research offers important insights into the future of mRNA vaccines - (Photo: SHUTTERSTOCK)

Researchers, led by a team at the MRC Toxicology Unit at the University of Cambridge, found that the presence of the variant - called N1-methylpseudouridine - caused "unintended immune responses" in about a third of vaccinated people in the study.

Professor Neil Mabbott, an immunologist at the University of Edinburgh who was not directly involved in the research, said some of the molecules in these vaccines have been modified to make them more durable. This is to prevent our immune systems from destroying the vaccines before they have time to stimulate an immune response to the coronavirus.

'However, in the new study, the authors show that these modifications can sometimes cause cells to misread the vaccine's RNA information. When this happens, it can create abnormal versions of the coronavirus's spike protein (the spike protein is the protein that helps the virus enter the body's cells - NV)' , Professor Mabbott explained.

But the first thing to make clear, according to the study, is that in theory, an 'unintended ' or 'off-target' immune response could be harmful, but in this case, it did not cause harm to people who received the Moderna or Pfizer vaccines.

Redesigning mRNA Vaccines

By fixing the sequences most susceptible to these chemical errors, the Cambridge team was able to effectively redesign the mRNA vaccine: making only the intended protein and thus eliciting the desired immune response.

'This study is more about how we can optimise mRNA technology to continue developing game-changing new vaccines in the future, rather than identifying any serious problems with current vaccines,' added co-lead author Professor Anne Willis.

As billions of pounds are poured into the next wave of mRNA treatments for other diseases, it is essential that new therapies are designed to have no unintended side effects, Mr Willis stressed.

'We need to ensure that future mRNA vaccines are also reliable,' explains co-author Dr James Thaventhiran. ' Our demonstration of 'slip-resistant' mRNAs is an important contribution to the future safety of new vaccines.'

What do other scientists say?

Professor Sheena Cruickshank, an immunologist at the University of Manchester, who was not directly involved in the study, said: 'Importantly, there is no evidence that mRNA vaccines are associated with harm to the vaccinated. The study also did not look at the antibody response of patients after receiving mRNA vaccines. So it is unclear whether this 'faulty' mechanism has any impact on the efficacy or safety of current vaccinations.'

However, Professor Cruickshank stressed that this was an important study, aiming to improve and add to what scientists already know. At the same time, he warned that they could use the mRNA technology platform to design other types of vaccines in the future.

Sharing the same view with Professor Cruickshank, Professor Stephen Griffin - an expert in cancer virology at the University of Leeds (UK), who is not part of the research team - said: 'There is no evidence that the findings in this study are related to the side effects of the vaccine. This will have to be further clarified in the future.'

The new study was published in Nature - a 150-year-old scientific journal, the most prestigious and influential in the global scientific community.