Except that it's not a few hours, there is research showing it is a few months and it winds up in tissues that are never touched by a normal viral infection.
And you already destroyed your credibility by equivocating eating a steak to getting an injection.
And normal vaccines are better than getting the disease because they work. The vaccinated people I know get COVID several times a year. Vanishingly few "unvaccinated" people have had more than one infection and those that do measure the time between infections in years, not weeks.
If such research exists, you can link to a citation of the original research paper. You can find medical literature at the website Pubmed. Since sometimes it is difficult to narrow down a Pubmed search to return only the desired results, you can alternatively do a search in Google (Duckduckgo/Yahoo/Bing/etc.) and find the paper that way. You will know it is a legitimate link if the acronym "NCBI" or "NIH" shows in the link or it is a CDC or WHO link.
The lifetime of mRNA in the cytoplasm is a few hours. While it is possible for the nanolipid mRNA particles to persist for longer outside of a cell, they can't do anything. The mRNA can only direct the synthesis of a protein from inside the cytoplasm of a cell.
Also, I would be very interested to hear which tissues are never touched by a viral infection. If a cell exists in the body, it is covered in cell surface receptors. As long as a virus can recognize those receptors, that cell can be infected. It doesn't matter in which tissue the cell is, the only pertinent fact is whether a particular virus can attach to a cell receptor on its surface.
And you already destroyed your credibility by equivocating eating a steak to getting an injection.
When you eat a steak (or any other food), its protein, nucleic acids, and lipids leave your intestines and enter your blood. Once in the blood, they are distributed all over your body. A vaccine injection doesn't even go into the blood, it goes into muscle tissue where the lymphatic system collects it and delivers it to adjacent lymph nodes. If anything, you should be MORE worried about all of that cow DNA in your blood.
And normal vaccines are better than getting the disease because they work.
"Normal" vaccines do not actually do anything. The purpose of any vaccine is to induce an adaptive immune response, which is work done by the immune system, not the vaccine. Also, no "normal" vaccine can prevent 100% of illness in 100% of recipients. A recipient who is immunocompromised might not have an immune response to a vaccine at all and will remain susceptible to the disease.
The vaccinated people I know get COVID several times a year.
Really? Why do I find myself so skeptical of this statement, which I've already seen dozens of times on a variety of websites? Do you know a lot of immunocompromised people? If they are so immunocompromised that they keep catching Covid over and over despite being vaccinated, how is it that they have survived it multiple times? Each time you catch Covid, it causes more harm to the body.
In reality, of course, the vaccine induces the immune system to produce T-cells, B-cells, and antibodies that specifically recognize the spike protein that is on the surface of the SARS-CoV-2 virus. When the antibodies attach to the spike, they physically block the virus from attaching to a cell. The antibodies also signal to the macrophages to destroy the virus.
Of all the vaccinated people I know, only one has come down with Covid. And it was a very mild case which caused some sniffles and not much else. It was mild because he had those antibodies. Those of us who were quarantined for a week in the same room as him (we were travelling together) did not catch Covid.