In this Thursday, Sept. 14, 2017 photo buses await students at York Middle School in York, Maine. A shortage of school bus drivers in some communities in New England and across the country is causing headaches for school districts this fall. Credit: Robert F. Bukaty / AP

The state has returned York County to yellow territory, saying it’s unsafe for schools there to be open for full-time, in-person education.

Five counties are now designated yellow, with elevated levels of COVID-19 spreading throughout the state. That’s the state’s school safety designation that recommends a hybrid learning model for schools, in which students attend in person part of the week and learn remotely the rest.

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Androscoggin, Franklin, Somerset and Washington counties continue to be designated yellow. Cumberland, Hancock and Kennebec counties are still in green territory, but the state is watching them closely as those counties see rising rates of new cases.

As it downgraded York County’s school safety rating, the state returned Knox County’s to green this week, as its rate of 15.34 new COVID-19 cases for every 10,000 residents over the past two weeks dropped below the state average of 18.66. Knox County had seen its rate of new cases spike at one of the fastest rates in the state toward the end of October as the state was at the start of its current surge, and as the coastal county saw a number of new cases from a virus outbreak at the Woodlands Memory Care facility in Rockland.

Over the past two weeks, Androscoggin County has seen its case numbers grow fastest in the state, with 33.80 new cases for every 10,000 residents, almost double the statewide rate.

York County was the first Maine county to be designated yellow, when the state downgraded its safety rating on Sept. 4 as the southern county dealt with a surge of cases stemming from an Aug. 7 Millinocket-area wedding reception.

In the past month, Maine has continued to see an unprecedented surge in COVID-19 cases, with the state close to crossing the 10,000-case threshold. While a number of schools have seen virus outbreaks, state health officials have said the virus is generally not spreading widely in schools, which are adhering to a number of safety precautions, such as face covering requirements, social distancing in classrooms and limited interaction between groups of students.