The administration of Governor Janet Mills on Friday updated it’s COVID-19 health advisory system, which is being used to offer guidance for schools.

The update released Friday says Androscoggin, York and Oxford counties remain in the yellow category, which suggests a hybrid learning model at schools. Those counties have experienced rising positivity rates and new case rates per 10,000 people, exceeding the statewide averages.

Somerset County has been moved back to green, which allows for all in-person learning. Their case and positivity rates have fallen below the statewide average.

Cumberland and Kennebec Counties remain green, though they are being closely monitored by the state. New case rates in both counties have risen steadily over the past week, but their positivity rates remain below the statewide average.

Since the advisory system was put in place, none of Maine’s counties have been placed in the red category.

Health officials say evidence suggests schools are not a major source of coronavirus transmission. According to Maine’s CDC and Maine DHHS, over the last 30 days, the rate of new cases is 20.2 per 100,000 staff and students, compared to 49.8 per 100,000 people statewide, which is generally consistent with previous weeks.