One of the most common worries expressed against the new coronavirus vaccine is that, supposedly, injecting mRNA into a cell has the potential to alter the human genome.
I am constantly bombarded by my family with links to conspiracy theory and vaccine hesitancy websites. Notably, these links often feature scientists with high academic degrees.
One example of such links features professor Roman Zieliński, who -- among other claims -- warns that the new vaccine has the potential to alter human genome. Notably, his field of specialization is genetics.
The explanation he gives looks convincing and sound, at least to a layman like me. I will try my best to translate the parts of the interview I linked to that are relevant to this issue:
Journalist: Claims are made that mRNA included in the 'vaccine' against the SARS-CoV-2 virus (commonly called C-19) may have an impact on our human DNA. In what way? And what does it mean for an average Joe?
Roman Zieliński: Your question brings up Watson and Crick's Central Dogma of Molecular Biology. These scientists had earlier received the Nobel prize for developing the double helix DNA model. Accordig to their Dogma, which is a part of the foundations of molecular biology, the genetic information does not only flow from DNA through RNA to protein, but also in the other direction, from RNA to DNA. Information, therefore, circulates between these two nucleic acids. This means that every RNA molecule that enters a cell may be transformed into DNA and may join the genome.
And this indeed happens. Viral retrotransposons incorporated into the human genome are one example. Around 60% of the human genome consists of them. tRNA and mRNA move towards the nucleus in a similar way. Cells have enzymes known as reverse transcriptases that enable rewriting RNA into DNA. Such enzymes include the human telomerase and reverse transcriptase of viral origin.
The process of reverse transcription, that is rewriting ribonucleic acid into deoxyribonucleic acid inside a cell is an evolutionarily old mechanism. It would be odd if mRNA molecules brought into our cells by this "vaccine" was exempt from this mechanism. There are numerous threats posed by introducing this mRNA construct in this "vaccine". The possibility that it includes itself into the human genome and further impacts the expression of genes and their mutations is one of such threats. The potential of transgenes to impact genome cannot be overestimated and the results of genetic research on plant GMOs support this. Their mutagenic potential on the genome is even stronger than the potential of chemical mutagens.
I tried to do my research. I entered the terms Zieliński used into Wikipedia. It seems that the central dogma of molecular biology is indeed an instrumental principle of this field, even though it is called in a suspicious way ("dogma") and this principle indeed explicitly states that information may be transcribed from RNA into DNA. The Wikipedia article about telomerase indeed states that this is an reverse transcriptase enzyme present in human adults in, for example, "in male sperm cells (...) in epidermal cells, in activated T cell and B cell lymphocytes, as well as in certain adult stem cells". And so on.
I found a relevant Skeptics.SE answer: Can an RNA vaccine change your DNA permanently?. It states: "mRNA produced in a cell doesn't modify your DNA, and neither would an mRNA vaccine.", but this seems to contradict the aforementioned central dogma of molecular biology.
Finally, and perhaps most importantly, I found mainstream scientists deny such claims:
- "Injecting RNA into a person doesn't do anything to the DNA of a human cell," says Prof Jeffrey Almond of Oxford University.;
- Prof. Krzysztof Pyrć, responding directly to similar claims made by Zieliński on another occasion, says he cannot even imagine how can mRNA work in that way (impact the expression of genes).
- Dr Maciej Przybylski says a human body cell does not contain enzymes necessary for RNA to be included in human genome (but Zieliński mentioned such enzymes!)
Unfortunately, these are just denials. These scientists repeat that mRNA included in the vaccine cannot impact human DNA, but do not elaborate why and how it cannot.
This is, therefore, what I would like to ask in this question. Why is it not possible for the mRNA included in the vaccine to impact human genome? In particular, how does the central dogma of molecular biology not mandate such a possibility?