Sorry to take so long getting back to you but I've been unwell.
COVID-19 mRNA vaccines give instructions for our cells to make a harmless piece of what is called the “spike protein.” The spike protein is found on the surface of the virus that causes COVID-19.
From the very dodgy CDC site.
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html
We now know of course that the so called vaccine doesn't stay in the muscle but travels throughout our entire bodies and that's why the SALK institute recently announced it is not primarily a respiratory disease but a vascular one.
As I stated in an earlier post here, our bodies manufacture spike proteins all over the place, it is a process we all do every day. The Ace-2 receptor is specifically a docking port for enzymes having spikes. We would not stay alive without spike protein transfers.
The trick that the vaccine people managed to conquer was to isolate the mRNA portion of the virus's internal mechanism, This segment by itself is merely a shopping list used by the virus when it replicates, but in itself the mRNA is an inactive and inert identifier. This is indeed inserted into human cells by the vaccine, which in turn adds the viral identifier to our normal tissue cells. Once identified our own cells use the spike protein transfer that they already have the inbuilt capability to do to inject themselves into the ACE-2 enzyme in the bloodstream, and this is then carried around the body as you say. but it is now a rogue cell that is attacked by our own immune response. This mechanism is also nothing new to our bodies. We do this daily for all sorts of unusual or unwanted or damaged cells. Bacteria, viruses, infections, cuts, wounds injections. It really is nothing to fear since it is what we are constantly doing since birth. We were designed to do this. The mRNA is the only clever bit that human intervention has manufactured. The fact that hundreds of millions of vaccine doses have been successfully injected into arms without causing serious side effects says a lot to me.
We have the numbers now- We also have seen how effective the results have been. Even if there is a conspiracy to supply vaccines, and some are making a mint from it, that is not the main story. If the vaccine protects me and my family from a horrible disease, then I do not regret partaking of it. My childhood was full of inoculations and vaccinations. Polio, typhoid, cholera, smallpox, tuberculosis, measles mumps, German Measles. flu, pneumonia, Diptheria, whooping cough, etc. I have not had yellow fever, cholera, or ebola shots, but would have them if I need to travel to those areas where these diseases are rife. It makes sense to do this. Covid is just another one to add to the list,
The argument regarding vascular or respiratory is pointless. The virus itself is airborne but can enter the body through many different entry points where mucus is secreted - eyes, throat, lungs. It enters the bloodstream via the ACE-2 enzyme and becomes bloodborne, but it has the greatest effect on the respiratory system by lodging in the lungs and causing severe respiratory distress. It also causes blood clots anywhere in the body, so it is both vascular and respiratory, just like Sars-Cov1 and avian flu were. Because we were already exposed to Sars-1 then we developed a large base of knowledge and experience of coronavirus transmission and genome, so when sars cov2 appeared, we were not starting from scratch. Again, as I stated previously, we had already begun to design medicines that also used the spike protein as a transfer mechanism.
There is nothing magical or deceptive about the way the vaccines were developed. The science makes sense and the mechanisms were well understood and developed prior to the emergence of the virus. I am comfortable with the outcome we are benefitting from.
Update: Where I use the term spike protein, I should technically refer to it as the S-protein, since our body proteins do not stick out as spikes. The Cov-2 spikes are also glycosylated to disguise them from immune responses, but the normal angiotensin proteins that dock with the ACE-2 enzyme are of course not glycosylated.