Could a Vaccine Change Your DNA?

No. Here’s why — and how to debunk this myth when you see it shared by your friends.

My biggest fear: “What if the vaccine turns us all into CUTE ADORABLE PUPPIES because it CHANGES our DNA and we ALL LOSE OUR THUMBS? How will we OPEN OUR BOTTLES OF WINE??” Photo by Tamara Bellis on Unsplash

Listen, there are a lot of myths and misconceptions about vaccines — what they do, what they don’t do, how they work, and what they could do to us (either unknowingly, or as part of a sinister plot to modify the human population).

One of the popular rumors I’ve seen about upcoming COVID-19 vaccines? Claims that they can alter our DNA.

First: No vaccine can alter our DNA. Your DNA will not be changed by a vaccine.

Great! Now that this is out of the way, let’s talk about how this rumor got started — and how to combat it, if you see it online. (And if you spend much time on Facebook or other social media platforms, you certainly will see it online.)

Let’s talk about what’s in these vaccines, how our DNA works, and why the vaccine will not cause changes in our DNA.

mRNA Vaccines Are New — But Not Unproven

The first big, scary fact about the COVID-19 vaccines being tested is that they use messenger RNA, or mRNA — which has “never been approved for use in humans.”

This is true, but it shouldn’t cause fear. At some point, the iPhone, automobiles, and denim fabric were all brand new, but we still embraced the advantages of a new invention.

These new mRNA based vaccines, just like all vaccines, go through a rigorous approval process in the United States:

  1. Before any FDA-sanctioned trials occur, the pharmaceutical company will test any potential vaccine. It’s incredibly expensive to push a vaccine candidate through clinical trials, so the company wants to make sure it selects a winner!
  2. In Phase I and Phase II clinical trials, the vaccine is tested on a number of volunteers to ensure that it’s safe and doesn’t cause side effects.
  3. In Phase III trials, the vaccine is tested on groups of thousands of people. The goal is to see how effective the vaccine is on blocking the virus — but the FDA also closely monitors for any side effects and records them all.

This safety monitoring continues even after the trial concludes, with the FDA hovering like an anxious mother, ready to pull her children to safety.

So why are these vaccines mRNA based? Why are we trying this new approach now, in the face of a global pandemic? And how do we know that this won’t mess with our own DNA?

To understand, let’s look at how an mRNA based vaccine works — and don’t worry, it’s going to be easy to understand!

Information Flows Downhill — DNA to RNA to Protein

Let’s start with a truth that’s so fundamental, it’s often known as the central dogma of genetics:

Information is stored in DNA. That information is used to make RNA. The information in RNA is used to make proteins.

Except for a few edge cases, information doesn’t flow the other way. That is to say, cells don’t turn a protein sequence into RNA or DNA.

My favorite analogy for this is a set of builder’s blueprints for a house. The architect will have one master set of blueprints (the DNA). He may distribute copies of different sections of the blueprints (the RNA) to individual workers. The workers will use the blueprint copies to build the parts of the house (the proteins).

If the central dogma of genetics was a hill, DNA would be at the top and protein would be at the bottom. Information flows down the hill, from DNA to RNA to protein. Photo by Emanuel Kionke on Unsplash

No one looks at the house and decides to draw up a new set of design blueprints from what’s already built! Similarly, the architect won’t update his master blueprints from anything on the builders’ copies.

How does this relate to vaccines?

We normally use protein in vaccines. But scientists have long dreamed of using RNA to teach cells how to build their own defenses against a disease.

Let’s go back to our house analogy. If you give someone a finished house (the protein), they can certainly put it to use. But if you’re able to give someone the blueprint copies (the RNA) and they can assemble their own house, they have a lot more flexibility in how they customize it!

An mRNA based vaccine is great because it’s able to be used, by our own cells, to build just about anything, including defenses against a virus.

Are We Sure It Won’t Cause DNA Changes?

Short answer: yes.

Longer answer: that central dogma of genetics, that information flows DNA to RNA to protein, isn’t just a lesson from school. Proteins won’t alter our DNA, nor will RNA.

Admittedly, there is one exception to the central dogma; using an enzyme called reverse transcriptase, we can convert RNA back into DNA. This is used in some sequencing procedures, and by some viruses.

But reverse transcriptase isn’t present in people, or in any other mammals. And it’s not in the vaccine.

In fact, if you wanted to change your own DNA, you’d have a really hard time doing it in a meaningful way! Most of the changes that accumulate in our DNA over time are due to damage, such as from radiation, exposure to carcinogenic chemicals, or just breakdown from old age.

These changes, however, aren’t meaningful — they don’t make specific changes that we may want. Adding specific changes is something that’s incredibly complex, and we still don’t have a reliable method to do so.

If scientists could change our DNA with an injection, this could lead to cancer cures, genetically modified humans, super-athletes, super-geniuses, and more!

Why would they develop this technology — but instead of taking any of those avenues, try to secretly alter the genetics of everyone who gets a vaccine?

So, let’s wrap up. One more time, just to be clear: a vaccine, even an mRNA-based vaccine, will not change your DNA.

Yes, this is a new technology for vaccines — but that doesn’t mean that it’s excluded from the extensive testing that is required for all vaccines, mRNA-based or not. And during these trials, all participants are monitored for side effects.

Using mRNA gives scientists far more flexibility in producing the right products to fight off the virus: we’re giving the body a set of blueprints, instead of the finished product. But mRNA is not DNA, and it doesn’t become DNA in the body. These are temporary copies of the blueprints — the master set remains untouched.

These can be frightening times, and it’s sometimes tough to tell fact from fiction when it comes to science that could mean the difference between pandemic and cure. But as a rule of thumb, don’t trust a claim until you’ve seen proof — and no, a YouTube video does not count.

Looking for more science content, in clear and plain language? Be sure to check out Sharing Science!

PhD in genetics, bioinformatician, scientist at a Silicon Valley startup. Microbiome is the secret of biology that we’ve overlooked.

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