RFK Jr is wrong about RFK Jr is wrong about mRNA vaccines – a scientist explains how they make COVID less deadlyRFK Jr is wrong about

©️The Conversation
7th August 2025
Deborah Dunn-Walters

US health secretary Robert F. Kennedy Jr has announced he is cancelling US$500 million (£374 million) of research into mRNA vaccines, citing unproven concerns about their safety and long-term effects.

Kennedy has claimed that mRNA vaccines “encourage new mutations and can actually prolong pandemics” – a misleading statement that contradicts the scientific consensus on viral evolution and effects of vaccination.

But scientific research shows that mRNA vaccines have saved millions of lives.

As an immunologist, I’ve spent years studying how the body responds to SARS-CoV-2 and other respiratory viruses. Let’s be clear: there is no credible evidencethat mRNA vaccines cause viral mutations – genetic changes that occur as a virus copies itself – or that they’re ineffective against respiratory infections like COVID-19 or flu. These claims misrepresent both how viruses evolve and how vaccines actually work.

Unlike traditional vaccines, which introduce weakened or inactive parts of a virus to trigger immunity, mRNA vaccines work by delivering genetic instructions that teach our cells to produce a harmless piece of the virus (usually a protein found on its surface). This gives the immune system a preview of what to fight, so it’s ready if the real virus shows up.

Our bodies are constantly fighting off infectious organisms – viruses, bacteria and other pathogens – that rely on us as hosts to survive and reproduce. As part of this ongoing battle, viruses naturally mutate over time. This process happens with or without vaccines.

Each time a virus replicates, small copying errors can occur in its genetic material. Some of these mutations have no impact; others give the virus a competitive advantage, helping it spread more efficiently. That’s how new variants arise.

In the case of COVID-19, scientists observed that the virus was mutating from the start. Variants appeared both within individuals (“intra-host variation”) and between them (“inter-host variation”). Every so often, one version would gain a competitive advantage – spreading faster, evading immunity, or becoming more infectious – and take over. These are the variants you might remember: alpha, delta, omicron.

This is how evolution works: organisms reproduce and change, and some changes help them thrive.

The immune system’s defence

Now, let’s look at the other side of the battle: our immune system.

Some parts of our immune defence are always on: physical barriers like skin, and innate immune responses that are ready to fight anything unfamiliar. But our most powerful defence is adaptive immunity: a specialised response that targets a specific invader once it’s been identified.

This is where vaccines come in. When a virus invades the body for the first time, it can cause serious illness before our adaptive immune system knows how to respond. But vaccines, including mRNA vaccines, act like a rehearsal. They introduce a harmless piece of the virus (often a single protein) so the immune system can learn to recognise it and respond faster in the future.

mRNA vaccines work by delivering a snippet of genetic instructions to our cells, which then produce the viral protein temporarily. Our immune system then builds a response to it. This means we get all the immune training with none of the illness – unlike actual infection, which can be dangerous.

Vaccines don’t cause viruses to mutate. The mutations already exist – they emerge randomly and constantly during viral replication. What vaccines (and our immune systems) do is filter which variants survive.

When the original COVID-19 virus encountered a population with strong immune defences – built through vaccination or past infection – it was effectively stopped. That virus lost its competitive edge. But other, naturally occurring variants with slightly different surface proteins (the “outer coat”) could sometimes sneak past these defences. That’s how new variants emerged.

Importantly, neither vaccines nor natural immunity created those mutations – they simply selected which ones became dominant.

The good news

There’s a silver lining. Even when a variant partially evades immune defences, our bodies often still recognise parts of it. This is called cross-reactivity – and it can mean we get less sick, even with a new strain.

Over time, as we’re exposed to more variants through infection or updated vaccines, our immune system refines its response. It becomes better prepared to fight future versions of the virus – just like it’s done with flu and other infectious diseases.

COVID-19 hasn’t disappeared, but thanks to mRNA vaccines and our growing immune memory, it’s far less deadly than it was in 2020.

Despite the claims of high-profile figures like RFK Jr, mRNA vaccines do not cause viruses to mutate. Mutations are part of viral evolution: a natural process that happens regardless of our intervention.

What vaccines do is give us a fighting chance. They’ve saved millions of lives by reducing severe illness, hospitalisations and death. They remain one of the most powerful tools we have in the ongoing battle against infectious disease.

Ivermectin now a quack cure-all

During the second and third years of the COVID pandemic, skeptics began to hear more and more of an anti-parasitic drug that had been used frequently for animals and less so for humans.

Ivermectin has been approved by health authorities to treat humans with strongyloidiasis and onchocerciasis (river blindness): conditions that are caused by parasitic worms. Also there are topical ivermectin preparations used to manage skin conditions such as rosacea and external parasites such as head lice. Used as prescribed it is quite safe and has improved the lives of countless individuals in developing nations. Yet we weren’t hearing about ivermectin used in this manner. Thanks to disinformation and irresponsible repetition of dubious claims, ivermectin was being promoted as a means to combat COVID-19.

The anti-vaccination movement embraced ivermectin because it resonated with the “my body, my choice” mantra. Right leaning media identities promoted it in much the same illogical way as they had hydroxychloroquine. It had been used safely for decades, they argued, and thus was clearly a sound choice to combat COVID-19 symptoms. Yet hydroxychloroquine, had a pharmaceutical history as an anti-malarial and an agent to manage symptoms of arthritis and autoimmune disease, not in treating COVID-19. Ivermectin similarly, had no clinically proven background in the treatment of COVID-19. The clinical trials had simply not been done.

For skeptics, the issue was and is quite simple. Look toward reputable sources. Seriously examine the arguments in favour of ivermectin. Review the strength of research being cited. Place the issue in context. Keep an eye out for ideology. Check the profiles and backgrounds of key players, and so on. In short: Seek the evidence.

Initially there was the 3 April 2020 media release from Monash University. The Monash Biomedicine Discovery Institute announced a paper published in the peer reviewed journal Antiviral Research. The title, The FDA-approved drug ivermectin inhibits the replication of SARS-CoV-2 in vitro, was tantalising. An informative piece published in the Sydney Morning Herald on 22 October 2021 cites experienced drug developer Dr. Craig Rayner referring to the impact of the announcement:

“It was incredibly hyped,” Dr Rayner said. “I knew it was going to start a fire.” […]

“It’s not the best thing for Australia to become known for in terms of its contribution to the pandemic,” Dr Rayner said. “But that’s what it is, unfortunately. It has promoted vaccine hesitancy and people are dying because they’re taking a veterinary medicine that has not been proven.”

For those looking to grab the ivermectin ball and run with it, the media release was peppered with big names, other nasty diseases and potentially exciting findings. It has since been modified to include an FDA warning and offer clear disclaimers about ivermectin’s effectiveness. What mattered to those who would go on to push ivermectin as a safe cure for COVID-19, came from just a few paragraphs:

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