Dr. John Campbell, one of the people I've been trusting for good info throughout the pandemic posted an interesting video a few days ago. Apparently the CDC has been testing blood donations for seroprevalence of covid in blood donations and had found that roughly 49% of donors were showing covid antibodies as of March 21st. At that same point in time only about 13% of Americans had been vaccinated. Based on that he guesses that anywhere from 36-49% of people nationwide have actually been infected. (some are likely showing antibodies because of vaccination but many (most?) of the people have the antibodies because of previous infection, some of whom had also since been vaccinated making an exact number of previous infections impossible.) If this is accurate than asymptomatic, or at least minor symptomatic, cases are pretty common. And the low current case counts/hospitalizations across the country regardless of vaccination rate in any given region are a good indicator that we actually are getting close to a level of herd immunity.
https://www.youtube.com/watch?v=jJpyvAv-oFQ