I suspect one of the big problems in vaccinating the U.S. is the degree to which it relies on bottom-up action.
What I mean is that presumably you can identify the hospitals, clinics, and long-term care facilities in your state, deliver vaccines to those sites, and rely on their management to get their people vaccinated. But once you go past that, once you start allowing people who are 65 or 75 and older to be vaccinated, you are essentially asking those people to take some initiative.
At best, like me, their health care provider, Kaiser Permanente in my case, will notify them when they have vaccine available. But people who don't have a healthcare provider with resources will have to search out a pharmacy.
As I write I realize the situation is not that different for the flu vaccine. Apparently 60-65 percent have gotten that vaccine in the past.
Seems as if this is a situation where we don't know until we see the history.