https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html
It gives a "protein" which may be "on the surface" of the covid-19 virus, and trains your body to attack anything with that "protein". Whose to say they won't fucking introduce something in the future which mutates ie your intestines to have their protein all over them?
That’s definitely a theory of the antigens turning on genes related to cancer and suppression. Hence the lumps women are finding after getting the shot.
I think the bigger issue for the future will be auto immune system problems when people are exposed to mutated strains of the virus. We should see some aspects of long term effects in the next year.