The vaccines from Biontech / Pfizer and Moderna are considered effective agents against Sars-CoV-2. Both are based on mRNA technology, in which genetic material is channeled into human cells. Could this change the human genome? A fact check.
It seems too good to be true: a revolutionary biotechnology could save mankind from the coronavirus. The first vaccine approved in the West by Biontech / Pfizer uses so-called mRNA. There was previously no approved vaccine of this type anywhere in the world. The vaccine was not only developed in record time, but at 95 percent it is so effective that many scientists had not expected. Moderna’s competitor product is similarly effective and is also based on mRNA.
The abbreviation mRNA stands for messenger ribonucleic acid, which is also known as messenger RNA. mRNA vaccines consist of the genetic information for one or more specific components of the virus, in the case of the coronavirus it is the spike protein or parts of it. During vaccination, this genetic information is channeled into human cells. Once the mRNA has reached the human cells, thanks to the plan stored on it, they can recreate the virus protein and present it to the immune system. This triggers an immune response and the vaccinated person ultimately has a very low risk of developing Covid-19.
But the fact that Biontech / Pfizer’s BNT162b2 is a genetic vaccine makes some people feel uncomfortable. Fears are circulating in social networks that the mRNA from the vaccine could alter the human genome, which is dormant as DNA in the cell nucleus. Some opponents of vaccination even use mRNA vaccination compared to the genetic engineering of plants.
Klaus Cichutek, the President of the Paul Ehrlich Institute (PEI), which is responsible for the safety of vaccines, had already warned against “scare tactics” by opponents of vaccinations in this context. “Warnings about genetic damage are wrong and cause unfounded fears,” said Cichutek in an interview with the “Neue Osnabrücker Zeitung”. Fears that the new mRNA vaccines could change the genetic material of humans would “not correspond to the state of scientific knowledge”.
But what is this assessment based on? An overview of the most important points:
mRNA does not come into contact with human DNA
An important point: Everything that is important in the vaccination happens in the cell, but has nothing to do with the cell nucleus – but only there is the human genome, stored in the form of DNA. “The mRNA has (…) hardly any possibility of getting to the DNA, which is isolated in the cell nucleus,” said vaccine researcher Carlos Guzmán from the Helmholtz Center for Infection Research to “Zeit”. Inside the cell, the mRNA of the vaccine and the DNA of the genome do not come into contact with each other.
mRNA and DNA have different chemical structures
There is another exclusion criterion: “Integration of RNA in DNA is not possible due to the different chemical structure, among other things,” writes the PEI. Due to the chemical differences, the two biomolecules do not fit together and cannot form chains. The most important deviations: DNA consists of a double strand, RNA consists of a single strand. Both also use different sugar molecules as a framework. RNA and DNA also differ in one of the four organic bases that form the “rungs” of the biomolecules that look like ladders.
mRNA can be converted into DNA – but not that easily
But couldn’t the mRNA also be converted into DNA and then integrated into the genome? In fact, a conversion is possible – this is done by viruses such as the AIDS pathogen HIV, which transcribes its RNA genetic material into DNA. To do this, the virus uses an enzyme called reverse transcriptase. However, this is not present in human cells. “There is also no evidence that the mRNA taken up by the body cells after vaccination is transcribed into DNA,” writes the PEI.
mRNA is a natural component of the human cell
The mRNA contained in the vaccines is not a foreign substance, but something that is permanently used in human cells. It is also crucial for the production of other proteins – for this, part of the DNA in the cell nucleus is read and sent to the cell’s protein factories in the form of messenger RNA. Since the mRNA only has a messenger function, it is quickly broken down again. It happens so quickly that it was long doubted whether mRNA could even be used medicinally.
The virus also works with mRNA
The mRNA vaccine only mimics what the virus would do itself: When Sars-CoV-2 penetrates the cell, its genetic information stored as RNA (coronaviruses are RNA viruses) is also passed on to the protein factories of the cells, where the components of the virus are then recreated. Including the aforementioned spike protein, the blueprint of which is in the mRNA vaccine. Other viruses, such as cold viruses, also use the same principle.
There is already experience with mRNA vaccines
The Biontech vaccine BNT162b2 is the first mRNA vaccine to be approved. But research into the therapeutic use of mRNA has been going on for around three decades. In the past, mRNA vaccines have also been developed and have already been investigated in clinical studies. The Tübingen-based company Curevac, for example, had previously tested an mRNA-based rabies vaccine on humans.
mRNA vaccines have advantages over DNA vaccines
However, there are also vaccines that are not based on mRNA but on DNA – and these are built into the genetic make-up of the human cell by chance actually as “potential security risk “as it is in the Pharmaceutical Directory Yellow list is. But that precisely this cannot happen with mRNA, the researchers Deborah Fuller and Peter Berglund assessed as a “comparative advantage of mRNA (with regard to DNA vaccines)”, as they write in their study on mRNA vaccines published in June.
Conclusion: “There is no risk of mRNA being integrated into the human genome”, judges the PEI. However, this does not mean that mRNA vaccines generally do not involve any risks. It is true that previous studies show that the vaccines are well tolerated. According to the company, some of the vaccinated test persons experienced side effects such as fatigue, headache and joint pain and redness at the injection site. Similar reactions are also known from other vaccines and are also a sign that the vaccine is doing what it is supposed to: get the immune system up to speed. What is missing so far, however, is information about rare, possibly serious side effects, as these only become apparent after vaccination of many people and a longer observation period.