Health A to Z — 6 minutes
Do mRNA vaccines against COVID-19 change our DNA?
The short answer to this question is no. It is impossible, because the mRNA in these vaccines does not contain any instructions enabling them to enter the cell nucleus, where our DNA (chromosomes) is found, or to insert their RNA into this DNA. To combat COVID-19, two types of vaccine are currently available in Canada:
- Viral vector vaccines
- Messenger RNA vaccines
Viral vector vaccines have been in use for decades. The AstraZeneca and Johnson & Johnson vaccines use a harmless virus programmed to enter cells and produce small amounts of the S (spike) protein, which is what allows the SARS-CoV-2 virus to infect our cells. Our immune system then recognizes this foreign protein and can eventually neutralize viruses that contain it. The messenger RNA vaccines from Pfizer/BioNTech and Moderna work differently. Instead of using a viral vector, the vaccine includes a molecule called messenger RNA (mRNA) that contains instructions to produce the famous S protein. Once inside the cell, the mRNA transmits its instructions to small cellular structures called ribosomes, which produce the S protein. Just as with a viral vector vaccine, our immune system detects this foreign protein and learns to destroy the viruses that contain it.
The main advantage of the mRNA vaccine is that it is easier to manufacture than the viral vector vaccine. In addition, we now know that it causes fewer serious side effects such as clotting (thrombosis).
This is the first time that foreign RNA has been introduced directly into our bodies for immunization purposes. As with any new development, this technology raises concerns and questions. Some wonder if the injected messenger RNA could end up in our chromosomes, change the DNA of our cells, trigger certain cancers and turn us into genetically modified organisms (GMOs). Let’s look at why this is not possible.
The relationship between DNA and mRNA
DNA, or deoxyribonucleic acid, is a molecule that contains all of a living being’s genetic information. Made up of two very long spiral strands (the famous double helix), this genetic information is found in the nucleus of each cell, spread over 46 chromosomes in humans. However, outside the nucleus, ribosomes cannot directly read the genetic information of DNA to produce the proteins necessary for the organism to function.
Here is where mRNA, or messenger ribonucleic acid, comes in. This is a copy of a small piece of DNA that contains the information needed to produce a protein. The mRNA carries this information into the cytoplasm (the part of the cell that surrounds the nucleus), where the ribosomes produce the protein. Messenger RNA is highly unstable and fragile, breaking down rapidly while the original copy remains intact in the DNA of the nucleus.
How does a messenger RNA vaccine work?
The mRNA vaccine aims to trigger our immune response by letting our cells make the virus protein. After the injection, the mRNA ends up in the cytoplasm, where it initiates the synthesis of the S protein. Since it is impossible for the mRNA to enter the nucleus, it cannot interact with our DNA or modify our genes. So it is impossible to speak of GMOs in this case!
Why some scientists consider mRNA vaccines to be gene therapy
Since the origin of vertebrates 500 million years ago, it is believed that fragments of viral chromosomes have succeeded in integrating into human chromosomes. However, only viruses containing an enzyme called “reverse transcriptase” are capable of such a feat. SARS-CoV-2, a ribovirus (RNA virus), does not contain the information needed to produce the reverse transcriptase required to insert a copy of its RNA into our DNA.
Nevertheless, some scientists, such as the controversial French physician Christian Perronne, believe that certain fragments of viral chromosomes that we have integrated since the dawn of time could contain the instructions to make this reverse transcriptase. Consequently, it would be possible to integrate a copy of the SARS-CoV-2 mRNA into our chromosomes. However, none of the very numerous studies on the composition of the human genome have been able to demonstrate such a possibility.
Vaccines: myths and facts
Given the severity and high mortality rate associated with coronavirus infection, vaccination is the best option to end the pandemic. It is true that vaccines can cause side effects, but most of the time they are mild (pain at the injection site, chills, fatigue and fever) and of short duration. In rare cases, they are more serious (allergic reactions, clotting), but the benefits far outweigh the risks. One thing is certain: the transformation of our cells into GMOs is definitely not one of these risks.
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- Rozhgar A. Khailany, Muhamad Safdar and Mehmet Ozaslan. “Genomic characterization of a novel SARS-CoV-2,” Gene Reports (2020), Vol. 19, p. 100682, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7161481/?fbclid=IwAR1TO2yIGuhC--LILkEZMmG5sYveVVrJDsHrBjkdEDTqo3HUiZcrUWCdIBU.
- Pierre Barthélémy. “Les humains sont apparentés aux virus,” Le Monde [Paris], May 28, 2012, https://www.lemonde.fr/passeurdesciences/article/2012/05/28/les-humains-sont-apparentes-aux-virus_5986230_5470970.html.
- “Vaccin ARNm : l’appel solennel du Pr Perronne,” France Soir, December 3, 2020, https://www.francesoir.fr/opinions-societe-sante/vaccin-arnm-lappel-solennel-du-pr-perronne.