If I understand mRNA COVID vaccines correctly, they contain some RNA that is inserted into a cell, which then is instructed to produce the spike protein, which is typical for COVID-19 viruses. Once the body has produced an immune response to the spike protein, it is better equipped to fight the actual COVID virus. So far, so good.

How do we know that the cells that have spike proteins on them do not pose a threat to the body? It seems like such cells have some sort of protuberance that might interfere with all sorts of cell activity that require close cell interaction.

Moreover, how does the cell (or the body) know when to stop producing spike proteins? Does the mRNA just run out at some point and there is none of it left to enter new cells?

  • On the last para/point, yeah, the mRNA is degraded over time. medicalsciences.stackexchange.com/questions/25522/… Not too clear to me what kind of proof you expect for the 2nd/middle para. One cannot rule out any and all fantastic scenarios other than them not having been observed.
    – Fizz
    Sep 8 at 22:16
  • Also, some (MHC) "protuberances" are actually expected and part of how the immune system works in order to adapt to antigen cas.org/sites/default/files/inline-images/…
    – Fizz
    Sep 8 at 22:25
  • 1
    Also to expand on @Fizz a bit...it isn't special or unusual for the mRNA to be degraded. mRNA is degraded all the time in cells; it's a temporary signal. A lot of gene regulation is done by deciding when to make mRNA transcripts, and this wouldn't work if mRNA lasted a long time. Same thing with proteins: proteins are degraded all the time. If a cell doesn't keep making new protein, it all disappears. How do we know these cells aren't harmful? Because the people who get vaccinated very rarely show any problems. That's why we do the trials. Sep 8 at 22:30
  • It's also not special or unusual for external mRNA to end up in cells; it happens when you get exposed to any virus, whether it makes you detectably sick or not. Sep 8 at 22:31

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