In nearby Arkansas, vaccines are available only to people 70 and up. In Oregon, adults 75 and older weren’t able to make a vaccine appointment until Feb. 15. All of these state plans are evolving in real time.

The CDC is recommending that states prioritize health care workers and residents and staff of long-term care facilities — where nearly 40 percent of the nation’s more than 455,000 COVID-19 deaths have occurred. Most followed those recommendations, though Florida and Georgia added adults 65 and up to their top priority group, known as “Phase 1a” in many state vaccine plans.

Vaccine distribution after Phase 1a is where many states diverge. The CDC and the Biden administration recommend that vaccines gradually become available to older adults, since adults 65 and up account for 8 in 10 deaths attributed to COVID-19. The CDC also recommends states begin vaccinating certain types of essential workers, like police officers and grocery store workers, after working through Phase 1a.

A CDC advisory panel recommends states place people at least 75 years of age and “frontline essential workers” — including teachers, police officers, grocery store workers and postal employees — in their second phase of vaccine distribution (1b). But the actual vaccine plans are being drawn up by individual governors and state health officials, who aren’t obligated to follow CDC recommendations to a T.

Most states are currently grouping older adults in their second phase of vaccine distribution, referred to by many states as Phase 1b. But states haven’t agreed on age brackets: Rhode Island is focusing on adults 75 and up, while neighboring West Virginia, which initially vaccinated residents at least 80 years of age, is vaccinating those 65 and up and teachers and school staff who are at least 50.

These differences have fed confusion about who can get vaccines and when they’ll be more widely available. Even in states that have for weeks offered vaccines to their older residents, getting a vaccine appointment is still a challenge due to high demand. Many state plans say that older Americans will likely be vaccinated in the first half of the year. “There are complexities involved, and there’s going to be some learning as we go here,” says Megan O’Reilly, vice president for federal health and family issues at AARP, which is fighting for older Americans to be prioritized in getting COVID-19 vaccines.