It's important that the CARVac (mRNA vaccine) part of the treatment targets specifically (though how specific, I dont know) dendritic cells which are "professional" antigen-presenting cells in the immune system. During an immune response, dendritic cells gobble up antigens and present them on their surface to help train the immune system so it's more trying to hijack that (very important) part of the immune response rather than training the immune system (and resulting in the death of the "infected" cells) in the way we're used to understanding mRNA vaccines.
Quoting from it: “ And that's what you see with the intramuscular dose as well: a good part of the dose goes to the liver, but in that case there's a substantial effect in the muscle tissue itself, and it's longer-lasting (out to about a week of protein expression)”
So, yes, an mRNA vaccine (the current ones, anyway) likely causes a fair amount of Spike protein to be expressed in your muscle tissue, but no one has noticed it causing the death of large amount of muscle tissue [0], and despite some searching, I haven’t found any evidence that anyone really understands what’s going on.
[0] People produce cytotoxic lymphocytes that detect bits of spike protein displayed by MHC1, much like CAR-T cells detect whatever they’ve been engineered to target on the surface of cells. Yet CAR-T (sometimes) kills massive numbers of tumor cells, and mRNA COVID vaccines apparently don’t cause the death of massive numbers of harmless cells that took up some of the vaccine. I’m curious why.
It’s been a while since I’ve been deep in the field, but the basics are you’ve got a first order action and a second order action.
T cells in this instance are directly cytotoxic. They find the ligand they bind to, and they begin lysis of the cell to kill it.
Meanwhile the intent of the mRNA vaccines that so many of us received over the last several years was to get B cells pumping out immunoglobulins which would soak up virus, reducing severity/duration of illness and allowing time for the bodies other defences to swing into action.
They’re not the same mechanisms of action (or at least they don’t rely on the same levers at the same strengths). Like everything in the human body, it’s a stochastic process so bits of everything are happening at once
Regardless of the intent of the vaccines, the evidence is fairly clear that they induce a CD8+ response, and the manufacturers seem fairly proud of this fact. Here a paper I found in a few seconds of searching:
