Not as many as you might think, according to Reuters and the CDC.
The CDC said 117,142,879 people had received at least one dose, or 46% of US adults. Fifty-four million additional doses have been distributed. Some states are welcoming out-of-staters to come get a dose.
However, the NY Times has list of % vaccinated by state, and only 1 state has a vaccination rate above 46% (New Hampshire), as does Palau. I don’t know if either/both Reuters or the NY Times is providing accurate numbers. The NYT may be looking at all residents, while Reuters was looking at eligible residents. Those under 16-18 are not eligible to receive vaccine (age 16 for Pfizer, 18 for the other 2 vaccines).
According to the NYT, all but 9 states will have opened up vaccinations to all adults by April 14.
It looks like the country will split roughly in half regarding the choice of whether to receive an experimental, questionably safe and effective vaccine or not. And then what happens?