Readers like you keep news free for everyone.

More than 5,000 readers have already pitched in to keep free access to The Journal.

For the price of one cup of coffee each week you can help keep paywalls away.

Support us today
Not now
Friday 1 December 2023 Dublin: 2°C

FactCheck: Are RNA Covid-19 vaccines actually responsible for 'genetic manipulation'?

A tweet going viral raises the spectre of some vaccines causing lasting genetic change to our cells, but this is untrue.


A SOCIAL MEDIA post which has been shared widely in Ireland and other countries claims that some Covid vaccines are actually ‘genetic manipulation’. 

The viral tweet has claimed that any vaccine needing to be stored at -80 degrees, which is the case for some of the Covid vaccines, “isn’t a vaccine,” but is a “transfection agent, kept alive so it can infect your cells and transfer genetic material.”

The tweet warns that “this is genetic manipulation of humans on a massive scale.”

The original tweet that made the claim has been retweeted over 1,600 times and liked over 2,000 times. 

A screenshot of it has been shared in at least 300 separate posts on Facebook, according to social media search engine CrowdTangle, and it has over 10,000 likes, shares and comments on the platform. 

It is part of a growing trend of misinformation on social media raising unfounded concerns about potential Covid-19 vaccines. 

The evidence

Two of the three Covid-19 vaccine candidates that are closest to regulatory approval in the west need to be kept at cold temperatures: the Pfizer/BioNTech vaccine is stored at -70 degrees Celsius while the Moderna vaccine is kept at -20 degrees. 

The tweet refers to vaccines which are shipped and stored at -80 degrees, which suggests the writer was referring to the Pfizer/BioNTech vaccine. Both the Pfizer/BioNTech and the Moderna vaccines are RNA vaccines. 

Traditionally vaccines have mostly involved giving people a weakened or killed germ, or parts of a germ. RNA vaccines are different.

Inside our cells, RNA – ribonucleic acid -  is the code to make proteins. Unlike the famed double-helix of DNA, RNA is made up of a single strand that is easily chewed up by our enzymes.

Using RNA vaccines means that the immune system is not exposed to the actual virus. Instead, they allow human immune cells produce what are known as spike proteins, which cause the immune system to produce antibodies against the virus. 

In effect, they train the immune system to recognise and attack SARS-Cov-2 without ever having actually encountered it before. 

“The RNA is translated into viral proteins in the antigen presenting cells,” says Professor Kingston Mills, vaccine scientist at Trinity College Dublin. These are the cells that gobble particles and viruses, and display what a foreign protein looks like, tutoring other immune cells.

“This mimics what happened during viral infection,” says Professor Mills. “Viruses infect human cells and their RNA is translated into proteins and eventually viral particles.” The vaccine RNA cannot make a whole virus.

“With the RNA only a single type of virus protein is made [the spike protein] and this does not allow creation of virus particles,” says Professor Mills. It generates immunity “without the effects of an infection,” he adds.

There were no RNA vaccines licensed for people before this year, but they had been in development for many years and have proven to be the most promising Covid-19 vaccines so far.

RNA is more fragile than DNA and this vulnerability was a major hurdle in developing RNA vaccines before now. 

“The RNA concept was slow to take off because of the issues around the RNA being broken up [in the body],” says Professor Mills. RNA is not alive in any sense of the word.

Making the virus protein inside our own cells is similar to what happens in a natural infection, and this is an advantage for RNA vaccines, say vaccine scientists.

The virus spike is then recognised by our immune cells. B cells (which make antibodies) and T cells (which kill infected cells) become battle ready to take on the coronavirus usually a few weeks after the first injection of the vaccine.

Then, if the pandemic coronavirus enters your body, you are equipped with B and T cells to fight it and hopefully stop severe COVID-19. It remains to be seen if it prevents SARS-CoV-2 infection and transmission, but stopping illness and death would be a huge achievement.

In other words: the tweet is correct in saying that RNA vaccines transfer genetic material (RNA) to your cells -  but the RNA does not stay in your body. The RNA is translated into viral proteins in the antigen presenting cells. It does not genetically manipulate humans, as the tweet claims, since the RNA does not change our DNA.

Similarly, the claim that a vaccine is not a vaccine when it is kept at extremely low temperatures but is instead a transfection agent ‘kept alive so it can infect your cells’ is inaccurate. 

Transfection agents “are devices that promote the movement of nucleic acids [such as RNA or DNA] into cells,” explains Professor Mills. The lipid particle surrounding the RNA can be considered such an agent, but it is not alive, he adds.

“A transfection agent is simply something that gets nucleic acids like RNA or DNA into a cell,” says Dr Tom Moore, geneticist at University College Cork.  

In his lab, for example, he puts DNA into soap-like bubbles that will then fuse with cells and deliver the DNA inside.  The bubbles are considered transfection agents.  

Dr Moore says the tweet sounds “sciency,” but the writer “is implying that you are modifying the human genome with the vaccine – and you can rule that out.”

The cold temperature storage has nothing to do with it being “alive”, and does not change the fact that a vaccine is still a vaccine. 

RNA vaccines are kept at extremely low temperatures to slow down the chemical reactions that break apart RNA. 

“RNA is very fragile.  You need these colder temperatures to maintain their integrity,” says Professor Sheena McCormack, clinical epidemiologist at University College London, about storage of the vaccines.  ”You can make them more stable by changing the formulations, and the vaccine developers are working on that.”


The tweet in question raises the spectre of the virus causing lasting genetic change to our cells, but this is untrue.

RNA vaccines contain synthetic genetic material but do not genetically maniuplate people who receive them because the particles and RNA in vaccines biodegrade in the body and do not stay there.

What the vaccine does leave behind are immune cells that recognise the spike of the pandemic coronavirus, allowing us to react faster to the presence of the virus.

As a result, we rate this claim as MISLEADING. This means that the claim either intentionally or unintentionally misleads readers.

Anthony King is a freelance science journalist in Dublin and part of’s factchecking team. He tweets at @AntonyJKing


There is a lot of false news and scaremongering being spread in Ireland at the moment about coronavirus. Here are some practical ways for you to assess whether the messages that you’re seeing – especially on WhatsApp – are true or not.


Look at where it’s coming from. Is it someone you know? Do they have a source for the information (e.g. the HSE website) or are they just saying that the information comes from someone they know? A lot of the false news being spread right now is from people claiming that messages from ‘a friend’ of theirs. Have a look yourself – do a quick Google search and see if the information is being reported elsewhere. 

Secondly, get the whole story, not just a headline. A lot of these messages have got vague information (“all the doctors at this hospital are panicking”) and don’t mention specific details. This is often – but not always a sign – that it may not be accurate. 

Finally, see how you feel after reading it. A lot of these false messages are designed to make people feel panicked. They’re deliberately manipulating your feelings to make you more likely to share it. If you feel panicked after reading something, check it out and see if it really is true.’s FactCheck is a signatory to the International Fact-Checking Network’s Code of Principles. You can read it here. For information on how FactCheck works, what the verdicts mean, and how you can take part, check out our Reader’s Guide here. You can read about the team of editors and reporters who work on the factchecks here

Have you gotten a message on WhatsApp or Facebook or Twitter about coronavirus that you’re not sure about and want us to check it out? Message or mail us and we’ll look into debunking it. WhatsApp: 085 221 4696 or Email: