PHOENIX (AP) — Arizona will open COVID-19 vaccine appointments to anyone 16 and older starting Wednesday, joining the growing number of states lifting restrictions on who is eligible for the scarce but growing number of doses.

The change applies to state-run mass vaccination sites in the Phoenix area, Tucson and Yuma. State officials said the decision was made based on a review of vaccination data, dropping demand and an expected increase of supply in the coming weeks.

“The best thing we can do is allow everyone that wants to vaccine to get a vaccine to help build that confidence,” Gov. Doug Ducey, a Republican, told reporters. “Because there was some slack in the system in terms of appointments available, and now additional supply on hand, we can safely open it up.”

Vaccine demand has softened quickly after months of intense interest, with available appointments gobbled up within minutes of their release. On Monday, there were 58,000 appointments available from last week's release, said Dr. Cara Christ, head of the Arizona Department of Health Services. The state is also seeing a rise in people canceling or skipping their appointments, some of whom are likely getting shots earlier from pharmacies, she said.

Alaska, Mississippi and West Virginia have opened vaccinations to all adults, and several others have announced plans to do so in the coming weeks.

President Joe Biden has said he wants states to take that step by May 1 and seek to vaccinate everyone who wants a shot by the end of May.

“We’re earlier than we anticipated, and I think that’s a really good sign because we’re that much closer to the light at the end of the tunnel,” Christ said.

Even as Arizona rushes to inoculate younger people eager to get shots and with transportation to get to drive-through vaccination clinics in urban areas, thousands of older people remain unvaccinated.

Health officials plan to release public service announcements and social media advertising to encourage holdouts to be vaccinated, Christ said. Vaccines will become increasingly available in pharmacies, doctors offices and neighborhood vaccination events to reach people who don't speak English or can't travel to a mass vaccine clinic.

In Maricopa County, which publishes robust demographic data, just over 70 percent of people 75 and older — the group most likely face hospitalization or death if infected — have been vaccinated.

Ducey urged people 55 and older who are currently eligible for the vaccine to make their appointments soon before they face a crush of competition from younger people.

Age restrictions for appointments will be lifted starting at 8 a.m. on Wednesday through the Arizona Department of Health Services website. New appointment slots will be released every Friday. Officials said all of the mass vaccine sites can add thousands of appointments each day, and the state has boosted its computing capacity to handle the expected influx of vaccine seekers expected to go online to make appointments.

About 2.9 million vaccine doses have been given so far in Arizona, with 1.1 million people fully vaccinated, or about 15% of the population, according to state data. The Pfizer and Moderna vaccines require two doses, while the Johnson & Johnson requires only one.

Christ said 16- and 17-year-olds should ensure they seek appointments at state-run sites, which are exclusively administering Pfizer vaccines, the only ones approved for people 16 and older. Moderna and Johnson & Johnson vaccines, which are available through counties and some private pharmacies, are approved for people 18 and older.

State health officials on Monday reported 484 new confirmed COVID-19 cases in Arizona but no new deaths, marking another day of downward trends for the state in the coronavirus outbreak.

State health officials said the number of hospitalized patients with confirmed or suspected coronavirus infections decreased to 647 on Sunday, while the number of ICU beds used by COVID-19 patients fell to 180.

Arizona’s weekly percent positivity for COVID-19 diagnostic testing, an indicator of how much the virus is spreading in the community, is at a five-month low.

The Navajo Nation, which was the site of one of the nation's deadliest outbreaks early in the pandemic, on Monday reported no new coronavirus cases and, for the second consecutive day, no new deaths.