COVID-19 is surging again in Maine, with Cumberland County and eight other counties now classified as being at high risk for transmission of the virus, according to new data released by the U.S. Centers for Disease Control and Prevention on Thursday.

Maine’s other high-risk counties are Oxford, Androscoggin, Sagadahoc, Lincoln, Knox, Hancock, Penobscot and Aroostook. York, Franklin, Kennebec, Waldo, Piscataquis and Washington are medium risk, and Somerset County is low risk.

In counties where there is a high risk of transmission, the CDC recommends universal mask wearing indoors. Masks are recommended for at-risk people in medium-level counties. The designations are based on infection rates, hospitalizations and hospital capacity.

Last week, Maine’s southern and coastal regions had been removed from the list of those experiencing high levels of transmission, with Cumberland, Sagadahoc, Lincoln and Knox downgraded to medium risk. One week ago, Aroostook, Piscataquis, Penobscot and Hancock were the only counties at high risk. Piscataquis dropped to medium risk on Thursday, with no change in transmission levels in the remaining three counties.

Meanwhile, the number of people hospitalized in Maine with COVID-19 edged higher Thursday as the state reported 791 new cases of the disease.

A total of 228 people were hospitalized as of Thursday morning, according to the Maine Center for Disease Control and Prevention. That’s up from 225 on Wednesday and slightly below the three-month high of 231 patients hospitalized on Tuesday.

The number of critically ill patients dropped from 34 on Wednesday to 31 on Thursday. Two patients were on ventilators Thursday. No additional deaths were reported Thursday.

Maine and the rest of the Northeast continue to experience high rates of new infections driven by increasingly contagious strains of the coronavirus. While more contagious, the omicron subvariants circulating now are less likely to cause severe disease than earlier versions of the virus. Hospitalizations have not increased as fast as the infection rate in recent weeks, and the number of critically ill patients has remained stable.

As of Thursday, Maine had the nation’s 10th highest infection rate with 311 infections for 100,000 residents over the past seven days, compared to the national rate of 210 infections per 100,000 people, according to the U.S. CDC.

The nation’s top health officials said Wednesday that residents of states such as Maine should step up their efforts to slow the spread by masking indoors, avoiding crowds and testing themselves with at-home rapid tests, especially before indoor gatherings.

Since the pandemic began, Maine has recorded 257,749 cases and 2,337 deaths.