Federal officials estimate about 40 million vaccines will be available by the end of the month if both Moderna and Pfizer get US Food and Drug Administration authorization — only enough to vaccinate 20 million people, because two doses are needed for each person.

But even that number will fall short. Pfizer is only expected to have 6.4 million doses of vaccine ready by mid-December.

A CNN analysis of the state breakdowns of what they plan to receive shows all will fall short of what they would need to fully vaccinate health care workers and long term care residents. CNN was able to confirm the expected size of the first shipment of vaccine for at least 45 states.

Now states must decide how they will ration the vaccine among their top priority groups and how the small first installment affects the timetable of when groups down the line can be vaccinated. Some states are already being forced to triage — choosing which healthcare workers are a higher priority than others.