• It's possible that one, if not two, coronavirus vaccines may be available in December.
• Medicare, which insures much of the 65-and-older crowd, changed its rules so the program can fully cover a fast-tracked vaccine.
• However, preliminary planning and recommended guidelines suggest that not everyone in that age group will be prioritized when vaccination programs begin.

Older Americans eager to get vaccinated against Covid-19 may need to exercise some patience.

While Medicare — which insures much of the 65-and-older crowd — recently changed its rules so it can fully cover a fast-tracked vaccine, the availability of doses will be initially limited. And, individual states are tasked with actually distributing the vaccine and identifying priority populations to innoculate.

"I think there are still major issues to resolve with vaccine distribution, which is being primarily left up to states to work out," said Juliette Cubanski, deputy director for the Kaiser Family Foundation's program on Medicare policy.

"That includes which populations will be prioritized when it comes to getting the initial doses once they are authorized or approved," Cubanski said.

The specifics of each state's preliminary plans for who they will vaccinate first differs a bit, although they generally target the same broad categories for Phase 1 of distribution, according to the foundation. That is, health-care workers, essential workers and individuals at high risk.

As the coronavirus crisis continues to worsen in the U.S., there's optimism that at least one vaccine, if not two, may be available in limited quantities as early as next month. In the U.S., the coronavirus case tally is above 11.5 million with more than 250,000 deaths, accounting for about 20% of both the 56.3 million global cases and estimated 1.3 million Covid-19 deaths around the globe.

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On Wednesday, Pfizer and German biotech partner BioNTech announced they would seek emergency-use authorization from the Food and Drug Administration within days for their vaccine. The companies also said their vaccine is 95% effective overall — up from their earlier 90% estimate — with at least 94% effectiveness for those 65-and-older crowd.

The news came two days after Moderna said its preliminary data also shows a 94.5% effectiveness. Between the two of them, the U.S. should have enough doses to vaccinate 20 million individuals by the end of the year, Health and Human Services Secretary Alex Azar told CNBC on Monday.

Public health officials have said the vaccine will be released in phases. States are making plans based on guidance from the Centers for Disease Control and Prevention, as well as guidelines released in early October by the National Academies of Sciences, Engineering, and Medicine.

That group recommends a four-phase approach, with phase 1A targeting healthcare workers and first responders, and 1B focusing on individuals with underlying health conditions that put them at significant risk for serious illness, as well as older adults living in congregate or crowded settings (which would include nursing homes and the like).

All older adults who weren't included in phase 1 would be among the populations targeted in phase 2. The group notes that adults age 65 or older account for about 80% of reported deaths related to Covid-19. Recent CDC data shows that of nearly 224,000 Covid-19 deaths in the U.S., more than 177,000 were in the 65-and-older cohort.

Among the groups targeted in phase 3 would be young adults and children; phase 4 would cover everyone who wasn't included earlier. Exactly how long each phase would last is uncertain, as part of the timing depends on distribution logistics and vaccine availability.

States also are early in the process of boosting the number of providers and locations for administering the vaccine, according to Kaiser. Most of them also recognize that there probably won't be enough vaccine doses available at first to cover everyone targeted in phase 1.

For instance, there are an estimated 17 million to 20 million healthcare workers, according to the CDC. The estimated population of the 65-plus age group is 53 million.

Nevertheless, older folks generally can count on getting vaccinated before, say, healthy young adults.

"But when that will happen is ... still very much unknown," Cubanski said.