Vaccine supply is most certainly the overriding issue, currently. mkjeeves, the issue you're seeing with the gap between doses distributed to OK and doses administered is a result of two things:

1) we are holding back a substantial number of those doses for the 2nd dose. That policy may change with the announcement this morning from the Trump administration. If Oklahoma ceases to hold back the 2nd dose, which seems likely, we will see that gap close faster;

2) the vaccine scheduling tool went live later than anticipated, so we had effectively been stockpiling vaccine while we waited for the ability to schedule broader administration. With the scheduling tool live and appointments being scheduled, you should see a drastic reduction in the distributed/administered gap. In fact, we've already seen that reduction. Just last week, we were around 30% of distributed doses administered. Today, we are closer to 50%. That gap will close.

We have the infrastructure to administer. We just need more supply. But as I noted in another thread, ceteris paribus, I expect to see demand plateau in mid-Feb or March and we will then have more supply than demand.