22
$\begingroup$

I would like to understand the effect of an mRNA vaccine on more complex processes in the human body.

To what extent does this "artificial", external addition of mRNA interfere with the body's processes? It seems naïve to me to think that it cannot set processes in motion that can be passed on - positively or negatively - to future generations.

Do I have a wrong idea about "artificiality" or the processes in the body?

As far as I know, there are (permanent) processes going on in the human body to modify the genetic information that will be passed on to future generations.

I also wonder to what extent this "reprogramming" of the immune system places a (too) strong focus on COVID-19 and whether this can weaken the immune response to other diseases. I have a naive idea of a "point system" where only a certain number of resources are available for different disease control.

$\endgroup$
0

3 Answers 3

45
$\begingroup$

I can address some of the points made in the post.

One point about the "artificiality": I think there's one fact that's often overlooked in the discussion of mRNA vaccines. SARS‑CoV‑2, for example, is a positive-sense single-stranded RNA (+ssRNA) virus. That means, the information that the virus uses to replicate itself and which describes the "blueprint" of its components, is stored as a single RNA. This RNA can more or less directly be translated into corresponding proteins by the ribosomes outside the nucleus, just like the mRNA used by mRNA vaccines. So, during a "natural" infection with such a virus, the virus's RNA also gets inside the cells and is translated into proteins, just like with the "artificial" mRNAs by vaccines! But the way this RNA enters the cell is somewhat different.

With viruses, they dock onto the cell and release their RNA into the cell. With mRNA vaccines like the one by BioNTech/Pfizer and by Moderna, this RNA is packaged into lipids (the stuff cell membranes are made of), which integrate more or less directly into the cell membrane and release the RNA. With vector vaccines like the Sputnik V or the Oxford–AstraZeneca vaccine, a different virus is used to carry the RNA load and infect cells (in the case of AstraZeneca, an adenovirus is used which usually infects chimpanzees and is normally harmless to humans). RNA in any case is degraded by the cells within a short time and leaves no traces.

Regarding the permanent modification of genetic information in humans: the genetic information in humans is stored as genomic DNA in the cell nucleus. DNA has a structure similar to RNA, but they do not work together, so RNA can't be simply integrated into the DNA. For DNA to form proteins, which make up most of the parts of a cell, it needs to be transcribed into RNA, which then is further processed into mRNA. This mRNA is tagged with a molecular export factor, which it needs to pass through the nuclear pore complexes, which are the highly specific transporters between the nucleus and the cytosol. After an mRNA has been exported from the nucleus, this tag is cleaved, so it can't return to the nucleus. Additionally, only if genetic information of egg or sperm cells is altered, this change is actually passed to the next generation.

So in summary: mRNA from vaccines behaves pretty much like the RNA inserted by RNA viruses into cells. And it can't find its way into the nucleus, where the genetic information is stored. And even if that happens by some way, it would first need to get "reversely transcribed" into DNA to be integrated. Some viruses can in fact do that, like HIV, which can also break into the nucleus in some instances (or wait for a cell division). Simple, "naked" mRNA of a vaccine however can't do that, only in extremely rare circumstances where the cell is already infected by another virus like HIV, I suppose.

But maybe you were talking about what is called "epigenetic modification", which is the molecular modification of the genomic DNA, where the actual stored sequence information is not altered, but the way it is read is modified. This process however is mediated for example by methylation of parts of the genome, for example, and does not intrinsically have anything to do with mRNAs in the cytosol. It should be noted that epigenetic modification is usually also reversible, not permanent, but it can be passed to the next generation, just like the genome itself.

What you said concerning the immune system focussing too much on another disease: I don't know a lot of immunology, but usually, building an immune protection against one pathogen also strengthens resistance against others. However, problems concerning the immune system most often arise when the immune system "overreacts" to an antigen and starts attacking parts of its own organism (autoimmune reaction). This can in fact be triggered by vaccines, even by only mRNA (and its protein products), as well as "natural infections", of course. Clinical studies are in place to analyze these occurrences.

$\endgroup$
4
  • 7
    $\begingroup$ A nitpick - The Sputnik vaccine uses Human Adenoviruses (HAd26 and HAd5). The Astrazeneca/Oxford uses Chimpanzee Adenovirus (ChAdOx1, based on ChAd25). $\endgroup$
    – bob1
    Commented Nov 25, 2021 at 20:00
  • 4
    $\begingroup$ The last point may be about the (effective) "memory capacity" of the immune system (a zero sum thought). This could maybe be addressed in the answer by stating (and comparing) the number of different pathogens (both new and already recognised) we are exposed to every single day. I don't know the number - in the thousands per year? Thus the "memory capacity" of the immune system must be at least on the order of 100 times that. $\endgroup$ Commented Nov 25, 2021 at 21:38
  • $\begingroup$ Thank you @bob1 for the correction, I fixed it! $\endgroup$
    – panda-byte
    Commented Nov 26, 2021 at 12:57
  • 1
    $\begingroup$ Also thank you @peter-mortensen for fixing typos and adding Wikipedia links. I'm not sure if I'm qualified to comment on the "memory capacity" thing, maybe someone else could chime in to amend the post. $\endgroup$
    – panda-byte
    Commented Nov 26, 2021 at 12:57
4
$\begingroup$

As @panda-byte writes in great detail, the mRNA processes in our cells are a one-way street and there is no conceivably relevant way for an externally introduced mRNA to modify your DNA.

Do I have a wrong idea about "artificiality" or the processes in the body?

Very likely, yes, if you (like me) do not have much more than general public knowledge, maybe as provided in a few short lessons in school if you were lucky.

I also wonder to what extent this "reprogramming" of the immune system places a (too) strong focus

The immune system is vastly complex and has many different layers and components. There is no way for a layperson (including myself) to have any luck in applying our intuition to these things - we must trust the scientists on this.

One of the best resources I know of which gives you a view of the insane complexity is the video How The Immune System ACTUALLY Works – IMMUNE from the excellent "Kurzgesagt" channel. They provide the scientific sources as well if you wish to learn much more than appropriate for an answer here.

$\endgroup$
0
$\begingroup$

The information is passed to future generations mainly via egg cells and spermatozoa - as long as the genomes of these cells are not modified, there is no high risk (and, contrary to some antivax claims, mRNA vaccines do not modify any genomes). There may be some environmental effects on the immediate offspring, due to their contact with mother during pregnancy and breastfeeding, but these are also very limited.

On the other hand, the immune system of the vaccinated person develops new antibodies, which hypothetically might cause potential (over)reaction to other pathogens or manifest in new allergies.

Disclaimer: this is not an expert opinion, but a placeholder answer to motivate a deeper discussion. I will be happy to remove it as soon as the experts chime in.

$\endgroup$
3
  • 2
    $\begingroup$ The (unfounded) concern may be epigenetic changes (even if it wasn't directly mentioned in the question). Perhaps address that as well? $\endgroup$ Commented Nov 25, 2021 at 21:51
  • 2
    $\begingroup$ Re "new antibodies, which hypothetically might cause potential (over)reaction": Isn't the cytokine storm caused by something else than antibodies? (Not a rhetorical question.) $\endgroup$ Commented Nov 25, 2021 at 21:59
  • 1
    $\begingroup$ @PeterMortensen It might well be, but the cytokine storm is not the only concern. There are many kinds of autoimmune problems that include light harmless allergies and severe syndrommes. $\endgroup$ Commented Nov 26, 2021 at 11:33

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .