It was a blow many were braced for, yet the block on US funding for mRNA vaccines by Robert F Kennedy Jr’s health department has left scientists reeling, with some stating the move could make the world less safe.On Tuesday, the US Department of Health and Human Services (HHS) announced it would cancel $500m (£376m) in funding for mRNA vaccines, ending 22 federal contracts – including one with the pharmaceutical company Moderna for its bird flu vaccine for humans.“We’re shifting that funding toward safer, broader vaccine platforms that remain effective even as viruses mutate,” Kennedy said in a statement issued on Tuesday.In many ways, it is not a surprise: Kennedy has long been known to be a vaccine sceptic, despite saying he is “not anti-vaccine”, just “pro-safety”, and has himself spread misinformation around immunisation, including falsely calling mRNA Covid jabs the “deadliest vaccine ever made”.In the statement, Kennedy said HSS had “reviewed the science, listened to the experts and acted,” and went on to claim mRNA vaccines failed to protect effectively against upper respiratory infections such as Covid and flu.

Yet scientists have been quick to refute the claims, emphasising that mRNA jabs saved millions of lives during the pandemic and, contrary to Kennedy’s assertions, do not increase the mutation rate of viruses.“There is no scientific evidence that this is the case,” said Robin Shattock, professor of mucosal infection and immunity at Imperial College London.“Different viruses mutate at different rates, for example influenza virus changes on a seasonal basis, Sars-CoV2 continues to vary irrespective of whether individuals have received mRNA vaccines.”Kennedy has spent decades undermining vaccine science, including championing the debunked claim that “autism comes from vaccines”, yet his invective towards mRNA jabs has been particularly potent.“It is difficult to understand why these brilliant innovations should be the target of anti-science sentiment.

But such a sentiment is not logical and so difficult to explain with logic,” said Prof Andrew Pollard, the director of the Oxford Vaccine Group that led the development of the Oxford-AstraZeneca Covid-19 vaccine.What is clear is that since mRNA vaccines came to public attention during Covid, they have been mired in misinformation.Such vaccines contain messenger RNA (mRNA) – a single stranded molecule that carries genetic instructions that can be used by protein-making machinery in human cells to churn out specific proteins.As well as saving millions of lives in the pandemic, mRNA vaccines have huge potential in other areas, including cancer, with the researchers who paved the way for the technology winning a Nobel prize in 2023.“MRNA is important today especially because it allows new vaccines to be made so consistently and quickly in comparison with other technologies which are slower and much more complex to make,” said Pollard.

“If there was an influenza pandemic it would take five to six months to make a vaccine using the traditional – and old-fashioned – technology of growing the vaccine virus in hen’s eggs – but it takes just six weeks to make millions of doses with mRNA, which can be scaled to tens and hundreds of millions of doses much more quickly.”Yet sceptics were quick to spread false claims about the vaccines – from the idea mRNA integrates into recipients’ DNA, to allegations such vaccines have not been properly safety tested.While some have suggested vaccine hesitancy is tied to an anti-establishment worldview, in which elites and experts are viewed with mistrust, others see the situation differently.“I suspect the really hardcore anti-vaxxers just don’t understand the science of how mRNA works,” said Dame Kate Bingham, who led the UK’s vaccine taskforce during the early part of the Covid pandemic.Pollard added that claims mRNA vaccines are new and untested are somewhat ridiculous.

“The technology has an excellent safety record with some of the best ever information collected on them because of the huge clinical trials and, in real-world use, the availability of modern digital records in many countries in the pandemic,” he said, adding that while there were some common side effects such as a sore arm and fever, these were also seen with other vaccines and were not of serious consequence.And while there could be extremely rare side effects, such as an inflammation of the heart muscle known as myocarditis, these were typically transient.The new block on research funding has caused consternation among researchers, not least in the area of influenza where Pollard notes there is a constant threat of a new pandemic that is worse than Covid.“At this moment, the USA is dealing with a massive outbreak of H5N1 influenza in birds and cattle – with some spread already to the UK – so this is just the moment when we need more investment in this area before [or] in case such a virus jumps to humans,” he said.Yet not everyone sees only disaster.

“Will this dent what’s going on in the US? Unquestionably.Does that mean it’s negative for the world? Not necessarily,” said Bingham, adding that the UK has collaborations with both BioNTech and Moderna – companies that work on mRNA vaccines – and has invested in the Centre for Process Innovation (CPI)’s new £26.4m RNA Centre of Excellence to develop new RNA therapies and vaccines.Such research, she said, would bring global benefits.“The low and middle income countries didn’t use that much mRNA because [such vaccines required a] -70 degree cold chain, so it was difficult for them to deploy it,” she said.

“And so the sort of thing that CPI is going to be doing is, how do you actually turn those vaccines into thermostable vaccines that can be deployed more widely?”Pollard was less sanguine.“If one of the largest markets in the world decides not to invest in mRNA, manufacturers will be less willing to invest their own resources in the technology.I fear that the wider implications of this decision could be that the world is less safe,” he said.Experts have also warned the move could have implications beyond curtailing research.“While this development is not only a retrograde step for the development of mRNA vaccines, of greater concern, perhaps, is that it reinforces the impression that, in spite of his protestations, RFK Jr is anti-vaccine,” said Dr David Elliman, an honorary associate professor at UCL, adding that has implications, not only for vaccination programmes in the US, but around the world.

“At a time when vaccination rates are falling globally, we need to follow the evidence, not ideologically led beliefs,” he said,“Such misguided beliefs are likely to cause unnecessary suffering and death, particularly in children,”