Maine is advising Oxford County schools to move away from in-person instruction because the county’s rate of new cases of COVID-19 more than doubled in the past two weeks.

The change in the reopening recommendation, which came as the state also reported 20 new cases of the virus, means both Oxford and York counties are now classified as “yellow” in the state’s color-coded school advisory system, meaning there is an elevated risk of spread of the virus and a hybrid of in-person and remote instruction is advised.

All other counties in Maine remain “green,” meaning the risk of COVID-19 spread is low and in-person instruction is possible as long as physical distancing and safety requirements can be followed. The state also is closely watching Androscoggin County and plans to reassess that county, as well as Oxford and York, next week.

The new cases Friday bring Maine’s total case count since the pandemic started to 5,235 cases. The seven-day average for new infections is 34.9, compared to 28.6 a week ago. No new deaths were reported Friday.

After subtracting deaths and recoveries, there were 588 active cases of the virus statewide on Friday, a decrease of nine from the day before but an increase of 56 from one week ago.

On Thursday, the Maine CDC warned the public about the potential for exponential growth of COVID-19 infections in York County, urging residents to follow health precautions as the virus becomes prevalent in the wider community.

The CDC is continuing to monitor outbreaks there, including at Sanford High School and Sanford Regional Technical Center, the Sanford Wolves Club, Hussey Seating Company in North Berwick and the Ogunquit Beach Lobster House.

In a news release Friday, the Maine Department of Education said the changes to the advisory system, which is updated every other week, were made out of an abundance of caution. Schools still have the final say on how they will offer instruction and some have already made changes in response to the presence of the virus in their communities.

Oxford County, which was recategorized from green to yellow, has seen rapid and significant increases in COVID-19 prevalence, the Department of Education said. The rate of new cases per 10,000 residents over the last two weeks jumped from 4.66 cases to 10.69 cases, exceeding the rate of new cases in York County. Its two-week positivity rate increased from 1.6 to 2.1 percent.

Oxford is home to the ND Paper mill in Rumford, where at least 16 employees have tested positive for the virus and one person has died. In response, the school system, Regional School Unit 10, has closed four of its schools in Rumford and Mexico and moved students to online learning for the next two weeks.

In York County, the rate of new cases per 10,000 residents over the last two weeks increased from 7.66 to 9.44. Its positivity rate remains at 2 percent and the Maine CDC has opened eight outbreak investigations in the last two weeks.

Sanford schools have moved to remote learning for high school and middle school students and the superintendent earlier this week announced the district would be partnering with the Maine Department of Health and Human Services to offer free COVID-19 testing for all students and staff at the high school and technical center, which have reported 13 cases between them.

The state also is closely monitoring Androscoggin County, where new cases per 10,000 residents over the last two weeks increased from 3.79 to 6.37. The positivity rate increased slightly from 0.6 to 0.7 percent.

Some school districts are also reporting staffing challenges amid the pandemic. In the Yarmouth School Department, where there has been one case of COVID-19, the school committee voted Thursday night to maintain hybrid instruction for the time being.

In a letter to families Friday, Superintendent Andrew Dolloff said bringing all students back in person would be impossible in part because the district is already short a dozen employees needed for hybrid instruction and another dozen would be needed to move to all in-person instruction.

“Our list of available substitutes has dropped from more than 110 to 25 – and those individuals are shared among several school districts,” Dolloff said. “Already this year, with minimal staff absences to date, we are experiencing days where positions are left unfilled – a situation that is likely to worsen as the school year progresses.”

Waterboro-based Regional School Unit 57 also announced Friday that Massabesic Middle School would move to all-remote learning for at least two weeks starting Monday after a positive case necessitated quarantine for some students and staff.

Staffing shortages resulting from the necessary quarantines were a factor in the need to move the entire school to all-remote, according to a letter to the community from Superintendent Larry Malone.

Maine continues to boast low per capita case numbers when compared to other states around the country. According to the New York Times’ COVID tracking project, Maine’s rate of 389 cases per 100,000 people is higher than just one other state, Vermont. Hospitalizations also remain low, with just 10 people hospitalized with the virus in Maine on Friday, according to the state CDC.

Waterville’s Northern Light Inland Hospital reported Friday that several of the 10 hospital staff members quarantined last week had returned to work and that no further staff members have needed to be quarantined.

Two of the 10 tested positive for the disease, which they are believed to have contracted from an infected patient when off site and off duty. They were potentially exposed again during visitation hours at Inland where the patient was being treated before being diagnosed with the disease, the hospital reported Sunday. The eight other staff members who isolated last week were believed to have had either prolonged face-to-face contact with the patient or prolonged exposure to those who had.

The staff members who have returned to work were determined to have not been exposed, but the others remain in quarantine, though they have tested negative for the disease, according to a statement issued Friday by Inland spokesperson Sara Barry. She did not disclose how many staffers had returned to work and how many were still in isolation, citing privacy concerns, but emphasized that the situation presents no risk to patients or staff.