Need to redo some numbers, Pfizer has been approved for ages 12 & up for a couple of months now [1]. Our World In Data lists that ~50% of American population is already fully vaccinated.
[1] https://www.fda.gov/news-events/press-announcements/coronavi...
18% of Americans are 15 or younger [1], below the youngest approved vaccine age (the Pfizer vaccine is approved for teenagers as young as 16), so that's (0.18 + (1-0.18) * (1-0.7) = ) ~42% of Americans who haven't even received 1 shot, and 58% who have.
(There may be some error in that, if far more or far less than 70% of non-adult vaccine-eligible people (teenagers aged 16 or 17) have gotten at least one shot, but it probably doesn't change the overall percentage that much.)
[1] https://www.cia.gov/the-world-factbook/field/age-structure