RUMFORD — Mountain Valley High School will switch to fully remote learning next week because of staff quarantined due to COVID-19 exposure, Superintendent Deb Alden said in a letter to the community Friday.

There are “around eight” staffers quarantining and others are out sick for other reasons, Alden said later Friday.

Alden’s letter said other Regional School Unit 10 schools, including Mountain Valley Middle School and Meroby Elementary School, both in Mexico, and Rumford Elementary School and Western Foothills Regional Program in Rumford “will be closely monitored throughout the weekend as staff and students get information regarding COVID test results and/or exposures.”

She asked the community to “stay tuned” Sunday to see if other schools will be included in next week’s closures.

Hartford-Sumner Elementary School in Sumner and Buckfield Junior-Senior High School “seem to have low (COVID-19 infection) numbers,” Alden said, and were not included in next week’s building closures.

Middle School Principal Ryan Casey also sent a letter to the community Friday saying a decision made in December to bring fifth and sixth-grade students who are in-person learners back into the building for four days a week rather than the current hybrid schedule of two days a week will remain on hold.

“We have many staff out of school due to required quarantines and cannot meet the CDC guidelines for health and safety at this time,” Casey said. The decision regarding a likely timeline for a four-day in-person school week for the fifth and sixth-graders will be made Jan. 15, Casey said.

Since early December, the Maine Center for Disease Control has designated Oxford County a moderate risk for spreading the virus. The next CDC notification on the level of risk in each county is Jan. 15.

The CDC suggests schools in counties designated as at moderate risk consider hybrid instruction to ease the spread of the virus. RSU 10 schools have included virtual and hybrid learning curriculum plans since March when the virus first affected Maine and the U.S. During the higher risk designation, the district does not hold its sports or extracurricular programs for students.