Maine added two more counties Friday to its list of those where it recommends schools offer hybrid instruction amid the state’s surge in coronavirus case numbers.

The Department of Education designated Somerset and Washington counties as yellow, meaning they have an elevated risk of COVID-19 spread. Hybrid instruction is recommended as a way of limiting the number of people in schools and classrooms at any one time. Waldo County, which received a yellow designation last week, remains yellow. The 13 other counties are green.

The changes come as Maine reported its highest single-day tally of coronavirus cases on Friday, with 103 new infections recorded around the state. In the last 30 days there have been 128 cases reported among students and staff in Maine schools.

The largest outbreak at a school so far has been at the Community Regional Charter School in Skowhegan and Cornville, which has reported 18 cases, though school officials said last week that everyone affected has recovered.

Most schools in Maine are already operating in hybrid models, but the transition hasn’t been easy and it’s even more complicated for schools that have had to shift between instructional models in response to cases.

“I’ve never had a problem that I felt so frustrated with,” Calais School Department Superintendent Ronald Jenkins said. “We’re getting bombarded in so many directions with what’s right and a different version of what’s right. It’s very difficult for us and I think that’s true of every superintendent in the state. It’s hard and quite frankly, they don’t teach you that in superintendent school.”

The Washington County district already opted to move to fully remote learning for its students Wednesday, so Jenkins said the state’s yellow designation won’t change things much. “We’re already following CDC guidance for the red designation,” he said.

Washington County is the site of a 27-person outbreak at Second Baptist Church, and the county’s two-week population-adjusted case rate is four times higher than it was last week.

Waldo County continues to have Maine’s highest per county positivity rate at 3 percent and a new case rate of 17.4 percent. No outbreaks have been identified in Waldo or Washington county schools at this time.

The state’s color advisory system, which is run by the Department of Education in conjunction with the Department of Health and Human Services and Maine Center for Disease Control and Prevention, is meant as a recommendation. Final decisions on instructional models are left up to individual school districts.

When the state launched the system in July, it originally said the advisories would be updated on a two-week cycle. However, the data is continually reviewed and Department of Education spokeswoman Kelli Deveaux said Friday that the timeline is not fixed and flexibility is necessary to ensure timely updates to schools. She said the significant increases in statewide cases necessitated Friday’s updates and that another update is anticipated next week.

While most of the state has been “green” since the start of the school year, meaning in-person instruction is allowed, most districts have opted for “yellow” models in order to adhere to the state’s required physical distance and safety guidelines. The DOE suggests that under a yellow model schools may want to take additional precautions such as suspending extracurricular activities and sports or limiting the number of people in buildings at one time.

Earlier this week the Maine Principals’ Association indefinitely delayed the winter sports season for schools around the state while the association works with stakeholders to develop COVID-19 safety protocols.

Mike Tracy, superintendent in Anson-based Regional School Unit 74, said he met Friday with other Somerset County superintendents, most of whom have districts that are already operating in a hybrid model. “For us, the major change is the cancellation of extracurricular activities and an abrupt end to the fall sports season,” Tracy said.

RSU 74 was forced to delay the start of the school year in August after a student tested positive for the virus, but Tracy said he has been pleased by what appears to be a low transmission rate for the virus in schools around the state.

“I’m really proud to say from my understanding Maine schools have not been the transmitter of COVID-19,” Tracy said. “The community spread in other places where they’re not taking precautions are where we’re seeing the transmission.”

In Skowhegan-based School Administrative District 54 in Somerset County, Superintendent Jon Moody wrote in a letter to the community Friday that the new yellow designation means that until further notice all sports, competitions and after-school activities will no longer occur in-person.

Because SAD 54 is already operating in a hybrid model, Moody said he didn’t anticipate any further changes to instruction other than a quarantine for some students and staff at Canaan Elementary School, where the CDC reported a probable case of the virus in a staff member on Friday.

In Calais, Jenkins said his district is moving to remote learning through Nov. 30 though they will re-evaluate on a weekly basis to see whether it’s possible to reintroduce any in-person learning. The district currently has two positive cases among elementary school students and additional presumptive cases among staff.

He said the district was prepared for the move to remote learning. Earlier this year the district used coronavirus relief funds to purchase additional technology for students, and teachers and staff have had professional development. Delivery of breakfast and lunch to students who request meals will also continue, he said.

“We hate what’s happening, but we know what we have to do,” Jenkins said. “Our first priority is to keep students safe and faculty and everybody. We’re trying to do it. I guess only time will tell how well we’re doing, but I’d like to think we’re doing a good job and everyone will be fine.”