Four of the Maine’s 16 counties remain in the “yellow” category for reopening schools, while increasing COVID-19 positivity rates in two other counties have them under watch by state officials.

Androscoggin, Cumberland, Oxford and York remain in the yellow category, the Maine Department of Education said in a news release Thursday afternoon.

Schools have been on holiday break since before Christmas, but will resume classes Monday with many of them offering in-person learning. Although schools have kept COVID-19 case numbers relatively low, the remote learning method adopted widely as a safeguard against exposure has been a challenge with some districts reporting rising failure rates.

The Department of Education 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.

Aroostook and Penobscot counties continue with a “green” designation, but the increased COVID-19 positivity rates in those counties are putting schools there in jeopardy of becoming yellow, the release said.

Maine schools have seen 602 COVID-19 cases in the last 30 days, according to the COVID-19 dashboard published by the Maine Center for Disease Control and Prevention, which was last updated on Dec. 24.

In the wake of the education department’s announcement Thursday, South Portland Superintendent Ken Kunin notified the school community that the decision had been made to go back to remote-only learning for Monday through Friday next week. South Portland had been planning to return to in-person instruction after the holiday break, but Kunin said the surge in COVID-19 cases influenced the district’s decision.

“While we had hoped to return to in-person learning on Jan. 4, we do think this is the most prudent course to take at this time,” he said. “This will allow learning to continue while providing time for assessing information on COVID-19 cases and exposure of students, families and staff during the December break.”

The school district also asked anyone who experienced COVID symptoms over the break or was exposed to someone who tested positive to contact their school nurse as soon as possible. Kunin said he will use that information to determine whether South Portland can return to in-person learning on Jan. 11.

Scarborough schools will implement a remote-learning model similar to South Portland, but over a shorter period. In a notice posted on the district’s website, Scarborough said that Monday and Tuesday will be remote learning days for all Scarborough students.

Delaying the start of in-person learning for at least two days will allow school staff and families to notify the district if they were infected or exposed to the virus over the holiday break. The district said that delaying the start of in-person learning also would help to alleviate any anxiety staff, students and families might have about returning to school.

The Portland school district has said it plans to return to a hybrid learning model – a combination of remote learning and in-person learning – when students return from the holiday break on Monday.

The state’s color advisory system, which is run by the education department in conjunction with the Department of Health and Human Services and the Maine CDC, uses a red-yellow-green designation to indicate the relative risk of virus transmission. The system is meant as a recommendation, with final decisions on instructional models left up to individual school districts.

Education Commissioner Pender Makin said Thursday that public schools in Maine are keeping their staff and students healthy and safe despite the ongoing surge in virus cases statewide. But she urged more support for precautions and protocols meant to stop the spread of COVID-19 in the broader community.

“Our schools are doing an amazing job of keeping staff and students safe, but they cannot be the one safe harbor in a community,” Makin said in a written statement. “Together we can get through this, but we need everyone to keep physical distance, limit any gatherings, wear masks, wash hands and stay home when sick.”

She said those precautions were making a difference in schools and that there were reasons to be hopeful in the New Year, but the virus and precautions to protect against its spread would still be with schools for the “foreseeable future.”

Makin also praised public school employees for the work they’ve done, as many schools are employing hybrid learning models with partial in-person learning and partial online classes.

“Throughout this pandemic, the workload for school nurses, teachers, school staff and administrators has been enormous and their collective commitment to providing the best education possible in the context of a pandemic is truly awe-inspiring,” she said.

The COVID-19 data is continually reviewed, and education department spokeswoman Kelli Deveaux has said the timeline for updating the color coding is not fixed, because flexibility is necessary to ensure timely updates to schools.

While most of the state has remained 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.

Over the last 30 days, the rate of new school cases is 33.5 per 100,000 staff and students, compared to 89.4 per 100,000 people statewide. “This rate of new cases in schools is 37 percent lower than in the general population and is consistent with previous weeks,” the department said in a news release.

At least 253 schools statewide from pre-K through grade 12 have reported cases in the last 30 days, including 53 schools with ongoing outbreaks of three or more cases, as of Dec. 24, according to CDC’s schools dashboard.

Staff Writer Dennis Hoey contributed to this report.