The number of COVID-19 inpatients at Maine’s largest hospital returned to peak pandemic levels this week, and other hospitals around the state are treating record numbers.

The number of COVID-19 patients admitted at Maine Medical Center in Portland had been rising slowly since mid-November, and rapidly increased from 16 to 35 over the week ending Thursday, a number that matches the previous peaks set on April 7 and May 25.

On Tuesday, when the patient count at Maine Med stood at 25, Dr. Joan Boomsma, chief medical officer of the hospital’s parent entity, MaineHealth, expressed concern about the rapidly diminishing capacity and the stress on staff at the hospital and its sister facility, Southern Maine Health Care Medical Center in Biddeford.

Boomsma wasn’t available for an interview, but on Friday evening MaineHealth announced that starting Monday it would reschedule “some, but not all, elective procedures” because of the growing number of COVID-19 cases. “Decisions about which procedures to be rescheduled will be made by clinicians on a case-by-case basis,” the nine-hospital network said in a news release that emphasized people to delay necessary care.

SMHC experienced its heaviest week of the pandemic, with an average of 20 confirmed COVID-19 inpatients treated each day for the week ending Thursday, when the patient count hit a record of 25.

Statewide COVID-19 hospitalizations also hit a new high of 144 on Thursday, though only 43 of these patients were in intensive care units, a healthier ratio than at other times in the past two weeks as the fall surge has hit the nation. During the spring surge, Maine’s worst day saw only 60 COVID-19 inpatients.

Three other major regional medical centers had their heaviest COVID-19 week yet, though cases appeared to be trending down at Bangor’s Eastern Maine Medical Center, which has been hit particularly hard by the fall surge so far. EMMC had an average of 24.3 confirmed COVID-19 inpatients being treated each day for the period, up from 23 the week before, marking the fourth straight record-breaking week. But on Thursday the hospital had 15 coronavirus inpatients, down from 29 four days earlier.

Dr. James Jarvis, physician incident commander for EMMC’s parent entity, Northern Light Health, said it was too early to tell whether the surge had crested at the Bangor hospital, to which acute COVID-19 patients from across northern and eastern Maine are typically transferred.

“The lower numbers of COVID-19 cases in patients are due to a combination of deaths and patients recovering,” Jarvis said. “We are seeing a shorter length of stay in general for those who recover than we have before, but the numbers are too small to tell a story.”

He, like other senior clinicians interviewed in recent weeks, said his hospitals have physical capacity to deal with the surge, but are concerned about staffing them as the risk of their employees getting exposed to the coronavirus while off-duty continues to increase. “The best way to keep them healthy and on the job is for everyone to follow good safety practices,” he said via email.

The pandemic is surging across the country, with nearly every metric striking the worst levels since the crisis began in the United States nearly nine months ago. States reported more than 216,000 positive tests and 2,857 deaths on Thursday alone, nearly as many as in the 9/11 terrorist attacks. Hospitalizations hit a record nationally as well, with 100,266 inpatients Thursday, according to the New York Times tracker.

Rhode Island opened field hospitals in Providence and Cranston last week, and Gov. Gina Raimondo called on health care workers to come forward to staff them. Massachusetts is opening a 220-bed facility this weekend at Worcester’s DCU Center in the expectation that some hospitals may soon be overwhelmed as acutely affected people exposed during the Thanksgiving holiday start to become sick enough to require admission.

Hospitals in Maine say they hope to meet demand by converting “swing beds” from ordinary medical-surgical duty to intensive care, while the Maine Center for Disease Control and Prevention has been dusting off contingency plans for field hospitals to be created at arenas in Portland and Bangor as hospitals continue to see unprecedented numbers of COVID-19 patients.

MaineGeneral again broke its record for the fourth week running with an average of 17.1 treated each day for the week ending Thursday, up slightly from 13.1 the previous week. During the summer months, there were many weeks when the Augusta hospital had no COVID-19 inpatients at all.

Both of Lewiston’s hospitals had their heaviest COVID-19 burdens so far. Central Maine Medical Center had an average of 12.1 such inpatients each day for the period, up from 9.3 last week and 6.6 the week before that. St. Mary’s reported 6.7 per day, up from 4.4 last week.

Mid Coast Hospital in Brunswick had an average of 4.3 COVID-19 inpatients each day, matching its busiest week in the spring, while at Portland’s Mercy Hospital the figure was 5.3, the heaviest week since the spring surge.

York Hospital saw a slight decrease in pressure, going from an average of 5.3 COVID-19 inpatients a day last week to 2.7 this week and had just two such inpatients Thursday. But the hospital’s lead infectious disease physician, Dr. Evangeline Thibodeau, said she remained concerned, as the hospital’s testing sites have seen the rate of positive results grow steadily from 1.3 percent to 5.5 percent over the past four weeks, suggesting the surge is building, not retreating.

“While last week may have been lower (for hospitalizations) than the two prior weeks, some of this may have been due to the Thanksgiving holiday,” Thibodeau said. “Holidays in general tend to be slower for hospitals.”

She said they are bracing for sharp increases in the wake of Thanksgiving travel and gatherings. “We will not see those cases in the hospital for two to three weeks after the holiday,” she said. “So time will tell.”

Smaller hospitals had COVID-19 patients this week as well. In the week ending Thursday, these included Franklin Memorial in Farmington, Sebasticook Valley in Pittsfield, PenBay Medical Center in Rockport, Blue Hill and Bridgton Hospitals, Acadia in Bangor, A.R. Gould in Presque Isle, Maine Coast Hospital in Ellsworth and Mayo Regional in Dover-Foxcroft.

Hospitalizations are a lagging indicator in that they typically occur one to three weeks after a person is exposed to the disease, but unlike other metrics they are not dependent on who and how many people were tested. They can end in three ways: recovery, death, or transfer to another facility.

The Press Herald compiles data directly from the hospitals and hospital networks. The data do not include outpatients or inpatients suspected of having the virus but never tested. The survey includes most of the state’s hospitals and accounts for the vast majority of the statewide hospitalizations reported each week by the Maine CDC.