Can the Pfizer or Moderna mRNA COVID Vaccines Affect Your Genetic Code?

The Pfizer and Moderna vaccines will become the mainstay of the COVID-19 vaccine rollout in Australia as the year progresses, according to recently released government projections.

As of September, an average of 1.3 million doses of the Pfizer vaccine plus an additional 125,000 doses of the pending Moderna vaccine per week are expected to be available. These numbers will rise from October as AstraZeneca vaccine use declines.

Both the Pfizer and Moderna vaccines are mRNA vaccines, which contain small fragments of the genetic material known as “messenger ribonucleic acid.” And if social media has anything to offer, some people are concerned that these vaccines could affect their genetic code.

Here’s why the chances of that happening are close to zero and some clues to how the myth came to be.

Remember, how do mRNA vaccines work?

The technology used in the Pfizer and Moderna vaccines is a way to give your cells temporary instructions to make the coronavirus spike protein. This protein is located on the surface of SARS-CoV-2, the virus that causes COVID-19. The vaccines teach your immune system to protect you if you ever encounter the virus.

The mRNA in the vaccine is taken up by the cells in your body and ends up in the fluid in each cell known as the cytoplasm. Our cells naturally constantly make thousands of our own mRNAs (to code for a range of other proteins). So the vaccine mRNA is just another one. Once the vaccine mRNA is in the cytoplasm, it is used to make the SARS-CoV-2 spike protein.

The vaccine mRNA is short lived and breaks down quickly after it does its job, as it does with all your other mRNA.

Vaccine mRNA resides in the cytoplasm and when it has done its job, it is broken down.

This is why the mRNA can’t be inserted into your genetic code

Your genetic code consists of a different but related molecule to the vaccine mRNA, known as DNA or deoxyribonucleic acid. And mRNA can’t insert into your DNA for two reasons.

First, both molecules have different chemistry. If mRNAs could routinely randomly insert themselves into your DNA, it would wreck the way you produce proteins. It would also scramble your genome, which is passed on to future cells and generations. Life forms that do this would not survive. That is why life has evolved in such a way that this does not happen.

The second reason is that vaccine mRNA and DNA are in two different parts of the cell. Our DNA remains in the core. But vaccine mRNA goes straight to the cytoplasm and never gets into the nucleus. There are no transporter molecules that we know of that carry mRNA in the nucleus.

But are there no exceptions?

There are some extremely rare exceptions. One is where genetic elements, known as retro-transposons, hijack cellular mRNA, convert it into DNA, and put that DNA back into your genetic material.

This has happened sporadically over the course of evolution, producing some old copies of mRNAs that have been spread throughout our genome to form so-called pseudogenes.

Some retroviruses, such as HIV, also insert their RNA into our DNA, using methods similar to retro-transposons.

However, there is a negligible chance that a naturally occurring retro-transposon will become active in a cell that has just received an mRNA vaccine. There is also a negligible chance of being infected with HIV at the exact same time as receiving the mRNA vaccine.

There is a negligible chance of being infected with HIV at the exact same time as having an mRNA vaccine.

Even if a retro transposon were to become active or a virus such as HIV were present, the chances of it finding the COVID vaccine mRNA, among the tens of thousands of natural mRNAs, are extremely unlikely. That’s because the vaccine’s mRNA is broken down within hours of entering the body.

Even if vaccine mRNA became a pseudogene, it would not produce the SARS-CoV-2 virus, but just one of its viral products, the harmless spike protein.

How do we actually know this?

There are no known studies of vaccine mRNA in the DNA of people who have been vaccinated. There is no scientific basis to suspect that this insertion occurred.

However, if these studies were conducted, they should be relatively straightforward. That’s because we can now sequence DNA in individual cells.

But in reality, it will be very difficult to ever satisfy a naysayer who is convinced that this genome insertion is happening; they can always argue that scientists need to look deeper, harder, into different people and into different cells. At some point, this argument will have to be laid to rest.

So how did this myth come about?

One study reported evidence for the integration of coronavirus RNA into the human genome in cells grown in the lab and infected with SARS-CoV-2.

However, that paper didn’t look at the mRNA vaccine, missed critical controls, and has since been discredited.

Such studies should also be seen in the context of the general reluctance of the public towards genetic engineering. This includes the public’s concerns about genetically modified organisms (GMOs), for example over the past 20 years or so.

But GMOs are different from the mRNA technology used to make COVID vaccines. Unlike GMOs, which are produced by inserting DNA into the genome, vaccine mRNA will not be in our genes or passed on to the next generation. It broke down very quickly.

In reality, mRNA technology has many applications in addition to vaccines, including biosecurity and sustainable agriculture. So it would be a shame if these efforts are held back by misinformation.

Written by:

Archa Fox – Associate Professor and ARC Future Fellow, The University of Western Australia Jen Martin – Leader, Science Communication Teaching Program, The University of Melbourne Traude Beilharz – Assoc Professor ARC Future Fellow, Biochemistry & Molecular Biology, Monash Biomedicine Discovery Institute, Monash University

Originally published on The Conversation.