The intensifying spread of the coronavirus has made it unsafe for schools to open full time in two new counties, the Maine Department of Education said Friday.

Four counties are now designated yellow, with elevated levels of COVID-19 spreading, more than ever before since the state education agency started issuing school safety ratings this summer.

The state on Friday downgraded the school safety ratings in Franklin and Knox counties from green to yellow as those counties recorded some of the state’s highest rates of new cases. Franklin and Knox join Somerset and Washington counties with the yellow designation.

The state, meanwhile, returned Waldo County’s designation from yellow to green, signaling that it’s safe for schools there to be open full time. The state, however, will reassess the county’s safety rating next week. After experiencing an outbreak of 60 cases connected to the Brooks Pentecostal Church last month, Waldo County’s rate of new cases has dipped below the statewide rate over the past two weeks.

Kennebec County, which has seen a number of new outbreaks in the past week, is also under close watch by the state.

Maine has consistently seen record-breaking numbers of new daily cases in recent days, along with a rising positivity rate — the percentage of coronavirus tests coming back positive — that’s a sign of the virus’ increasing spread.

The state has identified 30 new virus outbreaks — three or more related cases connected to a particular place — in the past two weeks, including at a handful of churches, a hospital, an athletic center and a number of other establishments.

Even with the dozens of new outbreaks, the state’s top public health official has said that the virus is spreading mostly outside of known outbreaks, with small, indoor gatherings a key source of new cases.

Somerset and Washington counties have recorded the highest rates of new cases over the past two weeks, with 23.77 and 19.76 cases per 10,000 people, respectively, as well as the highest positivity rates. Knox County has recorded 14.83 new cases per 10,000 residents over the past two weeks while Franklin County has seen 12.91. Both exceed the statewide rate of 9.15 new cases per 10,000 residents.

Although Cumberland County has seen 13.05 new cases per 10,000 people — slightly more than Franklin County — its safety rating remains green, as it has seen a lower positivity rate than Knox and Franklin counties.