There are signs the coronavirus pandemic is easing in Maine despite COVID-19 cases and hospitalizations remaining roughly static Friday compared with the previous day.

Recent wastewater testing shows lower levels of virus prevalence in Maine’s higher-population sewer districts, including decreases in Portland, Westbrook, Bangor, Brunswick, York, Bath, Yarmouth and Bethel. Lewiston-Auburn is a notable exception with the latest report indicating an increase in virus prevalence.

Wastewater testing is considered a leading indicator of pandemic conditions because the data is closer to real time than results of human COVID-19 testing. Water testing among the sewer districts captures data from the entire population, not just people who had their test results reported to the Maine Center for Disease Control and Prevention.

Many human test results are not getting reported to the Maine CDC, including those testing positive from at-home tests, or those who are COVID-19 positive but never got tested.

On Friday, Maine reported 168 patients were hospitalized with COVID-19, an increase of two from Thursday. There were 17 patients in critical care and four on ventilators. Hospitalizations have declined by about 27 percent since May 17, when 231 patients were hospitalized with COVID-19.

The spring hospitalization surge, fueled by an omicron subvariant, has resulted in substantially fewer patients in Maine hospitals. During the winter peak, 436 patients were hospitalized with COVID-19 on Jan. 13.

The Maine CDC also reported 510 new cases of COVID-19 on Friday. Since the pandemic began, Maine has recorded 262,097 cases of COVID-19, and 2,347 deaths. There were no new deaths reported Friday.

Cases are down 21 percent in Maine over the past 14 days, according to the New York Times COVID-19 tracker. Cases are increasing in much of the United States, although they are generally declining throughout most of the Northeast.

Meanwhile, COVID-19 transmission rates in four Maine coastal counties, including Cumberland and Sagadahoc, have been downgraded from high risk to medium or low, according to data released Thursday by the U.S. Centers for Disease Control and Prevention.

Cumberland, Lincoln and Knox counties are now in the medium-risk designation. Sagadahoc County, designated as high risk last week, is now the only Maine county listed as low risk. York, Kennebec, Waldo, Piscataquis, Washington and Somerset counties remain at medium risk.

For the second consecutive week, six Maine counties, including Androscoggin and Oxford, remained at high risk, the CDC reported in its weekly COVID-19 data tracker. Franklin, Hancock, Penobscot and Aroostook counties are also designated high risk. Franklin County was designated as medium risk a week ago.

With cases decreasing in Portland schools, and with Cumberland County now designated as medium risk, city schools will be mask-optional again starting Tuesday, May 31, according to a release Friday from the district.

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