MEMPHIS, Tenn. — The health department in Tennessee’s most populous county reinstituted a face mask requirement Wednesday for indoor public places such as restaurants, bars and other businesses as a surge in COVID-19 cases strains hospital resources and causes concern in schools.

A news release from the health department in Shelby County, which includes Memphis, said the mask requirement begins Friday and also applies to gyms, event venues and common areas of hotels and multi-residential buildings. The order also includes businesses such as retail shops, grocery stores and laundries, Shelby County Health Department spokeswoman Joan Carr said.

Masks can be removed for eating and drinking inside a restaurant or bar, and during workouts inside gyms, the health department said. Masks are optional in outdoor settings.

A countywide mask requirement was issued in 2020 for businesses after the coronavirus pandemic took hold, but officials lifted it earlier this year.

The move comes after strained Memphis-area hospitals sent a letter to government officials asking Shelby County to reimpose a mask mandate. The seven-day rolling average for daily reported cases was 638 on Wednesday, officials said.

Hospitals in Memphis and throughout Tennessee warned of a lack of staffing, and a dearth of intensive care and acute care beds, as the delta variant led to a surge in COVID-19 cases in recent weeks, including among children.

Among children 10 years or younger, there was an average of 549 new COVID-19 cases a day in Tennessee over the past seven days, compared to 347 for the seven prior days, state data shows. The previous high peaked at about 549 cases daily over a seven-day period in December. Currently, only those 12 and older are eligible for COVID-19 vaccines.

The school system in Shelby County, the state’s largest with more than 100,000 students, already has a mask mandate for K-12 students, faculty and visitors to school buildings, regardless of vaccination status.

Superintendent Joris Ray announced Monday that the requirement would stay in place despite an executive order from Tennessee Republican Gov. Bill Lee allowing parents to opt their children out of mask requirements by schools. The school system in Nashville also has kept its mask requirement in place.

Public health experts say masks are a key virus-prevention tool that does not pose health risks for children older than toddler age. The U.S. Centers for Disease Control and Prevention has again recommended them for schools.

Lee has resisted implementing a statewide mask mandate for schools, and had left the decision to local school officials. The Republican governor’s order lets parents opt out if either a school board or a health department enacts a mask requirement over a school district.

In announcing the order Monday, Lee said that while local decision-making is important, “individual decision-making by a parent on issues regarding the health and well-being of their child is the most important.”

With the order, Lee also said that for now he would not call a special legislative session requested by Republican House lawmakers to limit the authority of local officials to make rules related to COVID-19.

It’s possible the special session could be back on the table.

On Tuesday, Republican Senate leader Lt. Gov. Randy McNally said if Shelby and Nashville schools keep resisting, “we will have no choice but to exercise other remedial options,” without offering specifics.

McNally, who had favored letting locally elected school boards handle pandemic-related rules, deemed Lee’s order an “appropriate compromise.” He said he was “extremely appalled and alarmed” at how Nashville and Shelby schools reacted with defiance.

Lee’s order has drawn criticism from Democratic lawmakers, and from some parents and local officials in Nashville and Memphis.

In a statement Tuesday, the Metropolitan Nashville Education Association — an advocacy group for public school teachers — called Lee’s move “an example of a pattern of leadership that puts lives at risk.” In Shelby County, a caucus of Black county commissioners has called Lee’s order dangerous.

On Tuesday, Nashville district attorney Glenn Funk pledged not to prosecute teachers and school officials for enforcing school mask requirements.

But Amy Weirich, the district attorney in Shelby County, said it would be reckless for a district attorney to make a statement based “on a hypothetical situation.”

“What if a child is bullied or abused? A case like that would not be ignored by this office,” Weirich said Wednesday.

Meanwhile, in rural West Tennessee, an 850-student school district has called off classes for the rest of the week as it deals with a high number of students and faculty placed in quarantine.

West Carroll Special School District Director Preston Caldwell said 35 positive coronavirus cases have been reported and 350 students, faculty and staff were quarantined.

Fifteen percent of the Carroll County district’s faculty and staff were in quarantine, Caldwell said.

“It’s real, real tough, and it’s sad too, because kids want to be in school,” Caldwell said.