23.9% of the population has at least one dose of the vaccine. But if just looking at adults it is 30.7%. And 68% of 65+ have at least one dose of the vaccines.
We can also consider population immunity from infection. Estimates are around 30-40% have had a coronavirus infection. Adjusting for double counting that would raise the total immunity to ~55% of the adult population. Perhaps as high as ~80% for 65+.
Some caveats:
This is just a very rough double counting adjustment.
Natural infection suffers from some waning immunity. That probably eats into the infection immunity % a bit. And a decent amount of people were infected but didn't get an immune response to begin with. So deflating these numbers a bit is probably worthwhile.
And regional variation is large on both infection rates and vaccination rates on totals and by age. Some states are slow on vaccination like Texas or have broader vaccination rates by age like Pennsylvania. Others have low rates of infections like Hawaii.
And there's some indication in seroprevalence surveys that fewer 65+ have antibodies than <65 adults. Plus a recent study indicates they may have higher reinfection risk.