SEATTLE — Washington state’s top epidemiologist is recommending that everyone wear a mask or face covering in crowded indoor places because of the rise of the COVID-19 delta variant — even if they have been vaccinated.

Dr. Scott Lindquist said Friday the state is seeing a “fifth wave” of the new coronavirus that is sending more people to the hospital.

The state saw 2,572 new cases reported for Wednesday, July 21, compared with 750 seven days earlier.

The state Department of Health reports that about 350 people statewide are hospitalized with COVID-19, which is roughly half the figure for earlier waves of the pandemic.

“The majority of these hospitalizations can be prevented by people getting vaccinated,” Linquist said.

Washington state’s population is about 7.65 million.

The Department of Health and Gov. Jay Inslee aren’t formally reinstating mask mandates or other measures yet, Lindquist said.

Lindquist’s recommendation was echoed by the top public health official in Washington state’s most populous county, who on Friday also asked everyone to wear masks in indoor public spaces.

Dr. Jeff Duchin, health officer at Public Health – Seattle & King County, made the recommendation Friday. The advice is for both vaccinated and unvaccinated people.

Duchin said another factor driving up cases and leading to the indoor masking recommendation is the changing habits of people who stopped masking when a public indoor masking mandate was lifted on June 29, and people started gathering indoors and resumed traveling.

Duchin said his statement, too, was a recommendation, not a mandate.

“The level of vaccination we have achieved in King County will protect us from a severe outbreak that would threaten our health care system,” he said. “On the other hand, all of us need to be aware of the risk that the delta variant poses.”

More than 70% of county residents 16 and holder have been fully vaccinated.

The county’s seven-day average of new cases per 100,000 residents has increased to 41 from 19 on June 29, Duchin said.