But it doesn't make sense in this context. They're literally changing nothing except the mRNA sequence.
If a new vaccine is made by taking a gene sequence from a virus protein that's already in the wild, and packaging it into a delivery mechanism (LNP) that's already approved for another vaccine...
If there are any strange reactions to the new spike protein, that would also be caused by the wild virus spike protein, so it's an obvious competing harms situation where the vaccine should be approved, at least so long as the pandemic is ongoing.
Right, all you're changing is the mRNA, but that can still be really dangerous. What if you code for a protein that causes cross-reactivity with a human protein and you give millions of people an auto-immune disorder?
I'm 1000% pro mRNA vaccines and pro covid vaccines, but they still need to be tested.
Then the virus variant itself would cause autoimmune disease, and we'd have a much bigger problem than deciding whether to approve a new vaccine.
For fuck's sake, I'm not saying do no testing. I would assume they do basic checks, first in humanized animals, then using bioassays to try to detect all sorts of problems including antibody cross-reactivity with a wide variety of human cells. I'm also not against a preliminary limited human trial, with bloodwork checked after a few weeks to try to see if the assays missed anything obvious.
Short of that, what do you want them to do? We can't wait years to see if people develop symptomatic auto-immune problems. If we even wait 3-6 months for each new protein, the time advantage offered by mRNA or adenovirus vaccine tech is blown, or at least reduced to the point where there's no ability to react quickly to changing dominant viral strains in a pandemic, or new outbreaks of known diseases.
>Then the virus variant itself would cause autoimmune disease
You clearly have no idea what you are talking about or why the GP comment mentioned an autoimmune disease specifically. mRNA vaccines express specific proteins whereas the virus expresses entire viral molecules. A novel protein expression could cause an autoimmune disease because the novel proteins couls cause the immune system to attack the cells producing the isolated proteins, a problem you wouldnt have with cells producing entire viral bodies.
I think you misunderstood the (G)GP comment which mentioned cross-reactivity, i.e. the immune system's antibodies cross-reacted with both the spike protein and an endogenous human protein, like what can happen with Epstein–Barr virus Nuclear Antigen-1.
The immune system doesn't generate antibodies to an entire virus. It generates antibodies to specific immunogenic proteins or parts of proteins.
If the spike protein resulting from a vaccine causes an immune response that generates antibodies to the spike protein and oops, also some endogenous human protein, that's autoimmune disease.
If you get infected by a virus with the same spike protein, your body will generate antibodies to the same spike protein and also cause autoimmune disease if the antibodies are cross-reactive.
If cells expressing exogenous immunogenic proteins triggered autoimmune disease[1], even the existing wild-type (alpha variant) vaccines would cause autoimmune disease. Presumably that's not happening. The immune system may attack those cells expressing the exogenous vaccine-coded spike proteins, but normal immune systems down-regulate it well enough that it doesn't cause major problems. It would be a sign of a broken immune system if it decided to initiate a long-term attack of human cells just because they once expressed an immunogenic protein. If it did that, any virus would cause autoimmune disease.
Please tell me you work in a field related to immunology and you have a subtler point that I'm missing, and that you didn't just create an account to criticize a point you misunderstood yourself.
[1] to an unacceptable degree. Obviously, things can go wrong with the immune system and almost anything could, if you're unlucky enough, trigger an immune reaction leading to autoimmune disease eventually.
Harm ratio = harm caused by vaccine / harm caused by virus
Exposure ratio = projected people who would be infected by the virus / projected people who would take the vaccine
In an airborne, high-R_0 pandemic situation, the exposure ratio is high enough that only one of two cases apply:
1) The potential health problems caused by small-scale exposure to the spike protein alone is relatively small compared to problems caused by infection, in which case vaccinate everyone. This is the current situation.
2) The potential health problems caused by small-scale exposure to the spike protein are significant (for example, hypothetical antibody cross-reactivity with a normal human protein, as mentioned in a parallel comment), in which case obviously don't vaccinate everyone, but lock down the world for a few weeks since having much of the world suffer autoimmune disease is untenable.
The potential health problems are unknown. For example, we are assuming that Myocarditis/Pericarditis is extremely rare, or at least more rare than in a viral infection. Do we really know that, for all age groups and all vaccines? I have doubts, we are still in the discovery phase:
The spike protein is not necessarily a problem, but both NLP and viral vectors have never been rolled at the current scale. TTS seems to be particular to viral vectors, Myocarditis/Pericarditis more so to NLP.
> They're literally changing nothing except the mRNA sequence.
This is like comparing my house to the Willis Tower and saying, "they're literally changing nothing except the blueprints."
mRNA codes for proteins. Coding for a different protein will produce different effects in the body. Most will probably be harmless. If a vaccine codes for a protein too similar to proteins that already exist, that vaccine will produce autoimmune disease.
If a new vaccine is made by taking a gene sequence from a virus protein that's already in the wild, and packaging it into a delivery mechanism (LNP) that's already approved for another vaccine...
If there are any strange reactions to the new spike protein, that would also be caused by the wild virus spike protein, so it's an obvious competing harms situation where the vaccine should be approved, at least so long as the pandemic is ongoing.