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 are designated as medium risk.

For the second consecutive week, five 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.

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.

Meanwhile, COVID-19 hospitalizations continued to decline in Maine on Thursday and have now decreased by 28 percent since May 17.

Maine recorded 166 hospitalized COVID-19 patients Thursday, down from 177 on Wednesday. The patient count reached a three-month high of 231 on May 17, according to the Maine Center for Disease Control and Prevention.

Of those hospitalized Thursday, 15 were in critical care and four were on ventilators.

Also on Thursday, Maine recorded 556 new cases of COVID-19 and two additional deaths. Since the pandemic began, Maine has reported 261,587 cases of COVID-19 and 2,347 deaths.

Although seven-day daily averages have increased by about 31 percent nationwide, they are starting to decline in Maine and other parts of the Northeast, where subvariants of the highly contagious omicron strain hit earlier.

Maine’s seven-day average has declined by 11 percent over the past week, while Connecticut has declined by 15 percent and Rhode Island 9 percent, according to the New York Times COVID-19 tracker. New York and Massachusetts have experienced case decreases of 6 percent over the past week, while in New Hampshire cases have increased by 6 percent, and Vermont cases have gone up 14 percent.

While cases are down in Maine, the state still has the ninth-highest infection rate in the country, with a seven-day average of 43 cases per 100,000 residents.

Staff Writer Dennis Hoey contributed to this report