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No, covid-19 vaccines do not change your DNA

This article was published on
July 11, 2021

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The covid-19 vaccines approved in Europe are the result of technologies that have been in development for decades and are well understood. Researchers claim that none of them interfere with human DNA, as some hoaxers have spread.

The covid-19 vaccines approved in Europe are the result of technologies that have been in development for decades and are well understood. Researchers claim that none of them interfere with human DNA, as some hoaxers have spread.

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The first vaccines approved in Europe against COVID-19 —Pfizer/BioNTech, Moderna, Astrazeneca/U. Oxford and Janssen— use relatively new technology, with the Pfizer and Moderna vaccines the first of their kind. They are vaccines made from nucleic acids, the DNA or RNA molecules. This infographic provides a basic explanation of how they work and how they differ.

Unlike traditional vaccines, they do not contain any live micro-organisms —or fragments of them— so there is no chance of them causing the disease they are meant to prevent.

However, these new vaccines have raised another fear: that the DNA or RNA they contain will somehow interfere with the DNA of the vaccinated person. Experts are unanimous that this risk is non-existent.

DNA, RNA and proteins

DNA is the molecule that genes are made of, and genes hold the information needed to build the tens of thousands of different proteins that operate in living things. The genes of each individual human are containedin 23 chromosomes, which in the cells of our body are found in a special compartment, the nucleus.

For cells to make proteins from their genes, they produce a temporary transcript, the mRNA. Its function —put in very basic terms— is to take the DNA information out of the nucleus, and to have it translated into proteins. This RNA-to-protein translation process occurs in the cellular milieu outside the nucleus, the so-called cytoplasm of the cell.


The vaccines currently approved in Europe against COVID-19 deliver genetic information from the SARS-CoV-2 coronavirus into body cells. There it then leads to the manufacture of a part of the spike protein, which the virus uses as a key to enter human cells

The Pfizer/BioNTtech and Moderna vaccines use laboratory-made mRNA, which is then taken up by the cells.  

By contrast, AstraZeneca and Janssen vaccines introduce a DNA construct by combining it with the machinery of the common adenovirus (these vaccines are therefore called recombinant vector vaccines).

It works!

When someone is vaccinated, their cells start producing the S protein from the virus. Their immune system detects it, warns that it is foreign and produces defences against it.

One of the great pieces of good news since the start of the pandemic is that this does, in fact, happen. It was by no means obvious. Although the idea of making nucleic acid vaccines was raised as early as the 1990s, its development has had to overcome significant hurdles. So much so that the Pfizer/BioNTech and Moderna vaccines are the first RNA vaccines ever used. Nevertheless, it is a well-studied technology. Over the past decades, research groups around the world have generated abundant evidence that the chances of success were reasonable.

But there are more reasons for its use. Nucleic acid vaccines are faster to produce than traditional vaccines, and their formulation is relatively easy to adapt to possible mutations of the virus.

They are considered safe and effective. Some conventional approaches such as killed whole viruses or weakened (attenuated) viruses also contain all parts ofthe virus. However, they are not all important for a vaccine to be effective, and can actually lead to unwanted side effects. In addition, with weakened viruses there is a small risk that the vaccine causes some symptoms of the disease. In DNA and RNA vaccines this possibility does not exist.

There is also no risk of interaction between the DNA or RNA in the vaccine and the DNA of the person receiving it.

Chocolate dragées

We first look at the case of RNA vaccines, which are made up of RNA wrapped in a tiny fat capsule. Margaret Liu, a pioneer in this type of vaccine, has compared them to a chocolate dragée (the RNA) coated in sugar (the fat). This RNA enters human cells, but not their nucleus, where the DNA of the vaccinated person is located.

When the vaccine is injected, macrophages —a type of defence cell— near the puncture site ingest the fat-wrapped RNA. Cellular machinery in the macrophage cytoplasm will translate the RNA information into proteins, so that these cells can now produce the S protein from the virus and place it on their outer membrane, to display it tothe outside world.

This “induces adefensive response in the body like that which would be generated to protect us from a natural SARS-CoV-2 infection,” as Paul Sax, an infectious disease expert at Harvard Medical School, explains on the website of the New England Journal of Medicine (NEJM).

“Cellular enzymes then degrade the RNA that has been introduced with the vaccine. No live virus is involved in the process, and no genetic material enters the nucleus of the human cell. Although these are the first RNA vaccines to be used in the clinic, scientists have been working on them for years,” Sax adds.

Virus like a Lego truck

AstraZeneca's vaccine is a chimpanzee cold virus, harmless to humans, to which the DNA of the SARS-CoV-2 S protein has been added. In this case, when a person receives the vaccine, this DNA does enter the nucleus of their cells, “but at no time does it integrate with human DNA,” explains Santiago Elena, a CSIC researcher at the Institute of Integrative Systems Biology (CSIC-UV). 

“What happens when the vaccine DNA enters the nucleus is that the nuclear machinery recognises it and starts transcribing it into RNA,” adds Elena. “It is the same process as the attenuated virus vaccines used since the 18th century against smallpox: the vaccine virus uses the nuclear machinery to generate messenger RNA and, on this basis, in the cytoplasm, its proteins, but it does not interact with human DNA.”

The vaccine virus is actually a set of genetic commands that researchers have assembled one by one in the lab, knowing what each one does: “The virus is genetically modified, so it has only the instructions we want. It's like building a truck with Lego: if you want to, you can add a trailer with more or fewer pieces; if you don't, you just leave the tractor head... We control what we want it to do,” says Elena.

After a few days, the DNA of the vaccine disintegrates and is eliminated from the cells, but the human immune system will have already seen the S protein of the coronavirus and will be generating defences against it.

This article is also available in Spanish

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Expert Comments: 

Professor Santiago Elena

What happens when the vaccine DNA enters the nucleus is that the nuclear machinery recognises it and starts transcribing it into RNA. It is the same process as the attenuated virus vaccines used since the 18th century against smallpox: the vaccine virus uses the nuclear machinery to generate messenger RNA and, on this basis, in the cytoplasm, its proteins, but it does notinteract with human DNA.

The virus is genetically modified, so it has only the instructions we want. It's likebuilding a truck with Lego: if you want to, you can add a trailer with more or fewer pieces; if you don't, you just leave the tractor head... We control what we want it to do.

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