Conservative estimates are that 1 in 3 people that have COVID are asymptomatic, and other findings in controlled groups have found that it can be as much as 80%.
Considering COVID is a novel virus we should have no protection from it so why is not affecting everybody? COVID is just a cousin of many other Coronaviruses our bodies deal with all the time.
It's accepted that T-Cell immunity is a real thing and that anti-bodies that we have established for various flu and common cold viruses also give us a degree of protection.
The cells that produce anti-bodies for Spanish Flu have been found in people 90years after that pandemic and T-Cells for SARS have been found in people 17years after that outbreak.
It's blindingly obvious that those with weaker immune systems and those that are generally unhealthy (older, unfit, obese) are the ones most at risk and vaccinations will help cover them.
and the younger fitter part of the population, in the main, will see it off as they have been doing.
There is every reason to expect us to be out of this much much sooner than later now have a vaccine(s) to cover those at most at risk.
https://www.advisory.com/daily-brief...3/asymptomatic
https://www.bbc.co.uk/news/health-52446965