OLYMPIA — All counties in Washington will move to Phase 3 of the state’s reopening plan starting March 22, bringing restaurants and other indoor spaces to 50 percent capacity, allowing outdoor gatherings of 400 people and increasing capacity for fans at high school and professional sporting events.

The new reopening plan will move back to a county-by-county approach, evaluating each county every three weeks to determine if they can remain in Phase 3 or move backward, Gov. Jay Inslee announced Thursday.

“We’re now at a point where we can safely move forward,” Inslee said.

Phase 3 allows for as much as 50 percent occupancy, or 400 people, whichever is lower, at all outdoor facilities, as long as physical distancing and masking are enforced. Similarly, all indoor spaces, including restaurants, gyms, movie theaters and others, can increase capacity to 50 percent occupancy, or 400 people.

Larger event venues can have as much as 25 percent capacity, or 9,000 people, whichever is lower.

The new phase also expands capacity for outdoor sport events. Outdoor sporting facilities with permanent seating will have as much as 25 percent capacity for spectators. This affects both professional teams, including the Mariners and the Sounders, as well as high school sports.

More guidance for specific industries will come next week, according to Inslee’s office.

The new guidance is a change from the old regionalized approach, which required regions of the state to meet three out of four data metrics before moving forward. No Phase 3 was included in that plan.

While there is no timeline for when a Phase 4 might be identified, Inslee said it is possible it could come sooner rather than later. It will depend on the state’s COVID-19 numbers and vaccinations, he said.

Counties will move on March 22 to allow the state to continue on its downward trend in cases, Inslee said.

“If you look at the curve, we are seeing some progress in this regard, but we need a little more time to give us a higher level of security,” he said.

The Phase 3 announcement came on the same day that state health officials warned that case counts have plateaued and an additional variant has been identified in Washington.

“Our case counts have plateaued now in Eastern Washington, with an increase slightly in Western Washington (cases) among younger adults ages 20-39,” Secretary of Health Dr. Umair Shah told reporters Thursday. “This is an early warning sign of larger surges in the general population.”

The number of variant cases has increased statewide, as well, a sign that also has public health officials concerned .

There are 105 variant cases confirmed in nine counties statewide, now including one case of the variant traced to the United Kingdom confirmed east of the Cascades in Benton County, according to a state report.

Health officials have confirmed a third variant in the state as well, which so far has only been found in a handful of states nationwide.

The P.1 variant, which originated in Brazil, has been detected in King County. This variant “contains a set of additional mutations that may affect its ability to be recognized by antibodies,” according to the Centers for Disease Control and Prevention.

There are only 17 P.1 variant cases confirmed nationwide thus far.

“I am concerned about where this sets us up for the future,” Acting State Health Officer Dr. Scott Lindquist told reporters Thursday.

He also echoed Shah’s concerns about the state’s current case status, noting that while cases have plateaued, there are as many cases confirmed statewide on a daily basis as there were in October, just before the state’s largest surge.

“After every wave, we have a higher baseline, which sets us up for a continued wave,” Lindquist said. “I am very concerned about the possibility of a fourth wave.”

Counties will face their first evaluation on April 12 to determine if they can remain in Phase 3.

To remain in Phase 3, large counties must have fewer than 200 COVID-19 cases per 100,000 people every two weeks and fewer than five hospitalizations per 100,000 people every week. Counties with less than 50,000 people must have fewer than 30 cases every two weeks and under three hospitalizations every week to stay in Phase 3.

To remain in Phase 2, large counties must have between 200-350 new COVID-19 cases per 100,000 people every two weeks and less than 10 cases per week. Small counties must have between 30-59 new cases per two weeks and less than five hospitalizations every week.

People incarcerated won’t be counted in a county’s case rate for the reopening plan, according to the governor’s office.

If a county fails one or more of the metrics, it will move back a phase, and if at any point the statewide intensive care unit capacity reaches more than 90 percent, the entire state will be back to Phase 1.

Inslee said the system is built to allow for counties to move backward if cases begin to rise.

“But I am very hopeful that will not happen to any county,” he said.

Deputy Secretary for COVID response Lacy Fehrenbach said the state has the ability to stay in Phase 3 if everyone continues to wear a mask, get tested and stay home. Whether it’s COVID-19 or a variant from it, all of these actions can protect residents, she said.

Inslee said the ability to reopen is largely because of increased vaccine distribution, which he called a “night and day situation” compared to previous months.

He announced Thursday that all those in the next tier of vaccine eligibility will be allowed to get a shot beginning next Wednesday. That group includes agriculture, food processing, grocery stores, public transit, firefighters and law enforcement workers, among others. It also includes people 16 and older who are pregnant or have a disability that puts them at high risk.

State health officials encouraged residents 65 and older or 50 and older in multigenerational households to secure appointments for vaccines soon as eligibility is set to expand Wednesday.

Inslee’s news conference came just before an announcement from President Joe Biden to make all adults vaccine-eligible by May 1. In his first prime-time address since taking office, he laid out his plan, which includes lifting eligibility qualifications, deploying 4,000 troops to support vaccination efforts and allowing more people to deliver shots, according to the Associated Press.

It’s unclear how Biden’s announcement will affect Washington’s vaccine timeline as of now. When Biden announced teachers should all get at least one dose of the vaccine in the month of March, Inslee sped up the state’s timeline, saying he was constitutionally obligated.

The state hotline has scheduled more than 14,000 for vaccine appointments since late January, and those who cannot easily navigate the online Vaccine Locator tool can call 1-800-525-0127 and press # to make an appointment.

Scheduling appointments online through individual providers’ websites or different portals has been challenging for many people, and the Department of Health is working on a “one-stop shop” for residents to see all the available appointments and be able to book one through that site without having to navigate to several webpages. That work should be finalized in a week or so, Michele Roberts with the Department of Health said.

Vaccine allocations are increasing steadily statewide. This week, pharmacies in Washington received 72,000 doses from the federal program targeted to vaccinate teachers and health care workers.

Next week, the state will receive about 325,000 doses of COVID-19 vaccine, which is still less than what providers requested but an increase over past allocations.