Immunity is the ability of an organism to resist a disease. There is no doubt the vaccines boost immunity. Those who have been vaccinated are very unlikely to die from it or even get badly sick, even if they were in the high risk group. That’s compared to their prognosis if they were not vaccinated.
The young healthy people are vaccinated for the same reason young healthy people were vaccinated against polio and smallpox. If you are vaccinated it is highly unlikely your body will produce and spread the virus.
Covid had a big bunch of young people who had no symptoms but spread the virus, or it mutated in them as it spread.
When people who have already had covid are being being mandated or pushed into taking the FRANKENSTEIN VACCINES, common sense tells you the whole vax push has little to do with health.