📰 No, an mRNA vaccine is not gene therapy

Messenger RNA vaccines and gene therapies have very often been mistakenly confused: it has been claimed that these vaccines could “modify our genes”. Although the claim has been repeatedly refuted for a year and more.

1) Distinguish DNA from messenger RNA

We must first distinguish RNA from DNA. DNA (deoxyribonucleic acid) is a long molecule (A molecule is an electrically neutral chemical assembly of at least two atoms, which…) double-shaped helix (Propeller is from a Greek word helix meaning “spiral”. A shaped object…) which contains our information genetic (Genetics (from the Greek genno γεννώ = to give birth) is…). It is housed in the nucleus of cells.

DNA contains the instructions necessary for all stages of the life (Life is the name given 🙂 of an organism: survival, development, reproduction, etc. To perform these functions, DNA sequences must be converted or “transcribed” into “messages” for the production of proteins, the molecules that do most of the work in our bodies.

This transcription is done by enzymes present in the nucleus. They first read the information contained in the DNA, then thetranscribe into an intermediate molecule: this is the mRNA, or messenger RNA, of its full name messenger ribonucleic acid (Messenger ribonucleic acid, messenger RNA or mRNA is a transient copy of a portion…). Then, the mRNA is exported out of the cell nucleus: there, the ribosomes decode the information contained in this messenger RNA and translate in a language understood by the proteins that these ribosomes have the function of synthesizing. Since mRNA is unstable and fragile, it is destroyed quickly after fulfilling this “mission”.

2) What is the purpose of the mRNA vaccine?

Remember that the basic principle of any vaccination (Vaccination is a process of introducing an external agent (the…) is to trigger a response from our immune system (The immune system of an organism is a coordinated set of elements of…) against one virus (A virus is a biological entity that requires a host cell, which it uses…) and stimulate the production of so-called memory cells, which will protect us in case of infection. For example, this may be based on the administration, in the vaccine, of an attenuated or inactivated version of the virus or of certain of its proteins.

mRNA vaccines, such as those used against COVID-19, use an approach different (In mathematics, the different is defined in algebraic theory of…): they contain instructions to teach cells how to make a protein (A protein is a biological macromolecule composed of one or more…) specific to the virus. In this type of vaccines, the instructions are written in the form of a molecule of messenger RNA, hence their name “mRNA vaccines”.

To deliver its instructions to cells, the mRNA in COVID-19 vaccines, like those from Pfizer and Moderna, doesn’t have to need (Needs are at the level of the interaction between the individual and the environment. It is…) to enter the nucleus of cells, where our genes are. He only has to penetrate the rest of the cell, the cytoplasm (Cytoplasm refers to the contents of a living cell. More precisely, it is the…)to teach ribosomes how to make the spike protein specific to the COVID-19 virus, and create antibodies to fight it.

3) What is gene therapy aimed at?

In comparison, the therapy (A therapy is a set of measures applied by a therapist to a…) gene is to make deliberate changes to the DNA of a patient (In the field of medicine, the term patient commonly refers to a person receiving…)for example in order to cure or treat a genetic disease (Genetic diseases are diseases due to one or more abnormalities on a…)as’haemophilia (Hemophilia is a constitutional abnormality of blood coagulation related to a…) or cystic fibrosis. And for that, you have to enter the nucleus, where the DNA is and therefore our genes.

Concretely, it is a question of “introducing genetic material (in the form of DNA or RNA)” inside a targeted cell “to lead to a desired physiological effect”, summarizes the French Society of cell therapy (In the context of biotherapies, cell therapy aims to treat cells…) and gene. This can be done in several ways, such as replacing a embarrassed (A gene is a deoxyribonucleic acid (DNA) sequence that specifies the…) faulty by an alternative functional (In mathematics, the term functional refers to certain functions….)turn off a gene pathogenic (The term pathogen (from the Greek παθογ?νεια!…) or introduce a new gene to help immune cells recognize a sickness (Disease is an alteration of the functions or health of a living organism, animal…) and eliminate it, specifies the Food and Drug Administration (The Food and Drug Administration (abbreviation: FDA) is the American administration…) (FDA) of the United States.

4) Distinguish between RNA vaccine and gene therapy

One can understand the parallel that has been made: the two mechanisms consist of “introducing genetic material” into a cell. But there the comparison ends: the mRNA vaccine does not aim to alter our genes, and it cannot even do so.

The COVID mRNA vaccine only aims to teach our cells how to make the spike protein.

As it cannot penetrate the nucleus – separated from the rest of the cell by its own membrane – the mRNA vaccine against COVID cannot therefore interact with our genome (The genome is all of the genetic material of an individual or a…) or modify our genes, unlike gene therapy. “Nothing to do with the creation of a GMO,” quipped INSERM. And even if that strand of RNA had the amino acid sequence necessary to cross that membrane (called signal (General terms A signal is a simplified and generally coded message. There is…) nuclear localization), it would still need to be transcribed into DNA to make changes in our genes, which RNA cannot without a enzyme (An enzyme is a molecule (protein or RNA in the case of ribozymes) allowing…)called transcriptase.

Moreover, as we said above, RNA is a fragile and unstable molecule: once the piece of protein is made, the mRNAs are broken down by the cell. They will have disappeared a few days (The day or the day is the interval which separates the sunrise from the sunset; it is the…) after vaccination, according to the CDC.

In comparison, gene therapies can have long-lasting effects – that is their goal – because they permanently modify the DNA of the cell. These modifications being inherited by all the daughter cells which result from the division (Division is a law of composition which associates the product of the first with two numbers…) of the cell, they can persist for years.


Messenger RNA vaccines are not gene therapy because the genetic material they contain does not enter the nucleus of the cell, where the DNA is. They do not have the ability to integrate the genome or modify it.

Journalists: Catherine Crépeau and Ève Beaudin.
Infographics: Vincent Devillard

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