Denti's talking epidemiology
Covid19 spreads like the common cold; so, a strong probability just about all of us will be exposed to it over the next few years. Identified cases tend to be the severe ones, but at least that denominator (positive tests) is known. Silent infections are likely a much larger denominator that we don't really know at present.
As for a vaccine, they've been trying for many decades to develop one against a fellow coronavirus, the common cold.