Hospitalizations for COVID-19 remained flat at a high level across Maine for a third week running – an encouraging sign – but hit record levels at both of Lewiston’s hospitals.

The burden of caring for people acutely affected by the coronavirus has shifted around the state over the past two months in ways that have so far defied easy explanation, hammering Bangor’s Eastern Maine Medical Center in December before shifting south to hospitals in Portland and Lewiston.

“There’s a tendency to assume there’s a scientific reason for observed trends, and maybe there is,” Dr. Nirav Shah, director of the Maine Center for Disease Control and Prevention, told the Press Herald. “In any observational system, whether you’re looking at planetary motion or a pandemic, you have to allow for the possibility of what you are seeing is randomness.”

Both of Lewiston’s hospitals hit record levels of confirmed COVID-19 inpatients for the second week in a row. For the week ending Thursday, Central Maine Medical Center cared for an average of 16 such patients each day, up from 15.6 last week and 11.1 the week before. St. Mary’s Regional Medical Center had an average of 10.1 inpatients, surpassing the previous high of 7.4 set last week.

The pressure eased slightly at Portland’s hospitals, including the state’s largest. Maine Medical Center – which has 613 beds – reported an average of 39.3 inpatients a day for the week ending Thursday, down a hair from the record-setting 40.9 set last week and 38.4 the week before that. For Mercy Hospital the figure was 9.6 per day, down from 11.7 last week and that hospital’s record level of 14.9 set in mid-December.

The burden also continued to trend down at York County’s hospitals, with the 158-bed Southern Maine Health Care Medical Center in Biddeford reporting an average of 13.6 COVID-19 inpatients a day for the week compared to 14.4 last week and well below its record of 23.2 in late December. York Hospital, a 48-bed community hospital that was hit hard by the disease a month ago, cared for an average of 2.9 COVID-19 inpatients each day this week, down from 6.0 last week and 10.7 three weeks ago.

Dr. Gretchen Volpe, an infectious disease specialist at York Hospital, said via email that the number of active cases of COVID-19 appeared to be going down in their area. The percentage of COVID-19 tests coming back positive at the hospital, its practices and a drive-thru testing site on Route One in York has been going down, from over 11 percent in late December to around 7 to 8 percent in the second and third weeks of January. “However, the situation is certainly in flux, with the impact of vaccination and possible cases of infection due to COVID-19 variants yet to be seen,” Volpe said.

EMMC – which was the busiest COVID-19 hospital in the state for much of December – continued to see declining demand, with 19.6 COVID-19 inpatients a day, down from 25.7 last week. It stands far below its peak of 51.9 per day set at the end of December, which was the most demanding week experienced by any Maine hospital since the pandemic began. Nonetheless, it did not have to cancel many other procedures, and its officials have said intensive care capacity was never in jeopardy, in part because many beds in its newer wing were designed to be converted to ICUs.

The overall statewide COVID-19 inpatient level fell sharply Thursday to 171, the lowest it has been since Dec. 21. Fifty-one COVID-19 patients were in intensive care.

New hospitalizations – a different metric than inpatient nights of care – have also declined statewide, Shah said, from a peak of 18 a day in mid-December to 12-14 this week. ICU capacity statewide was “OK, not great,” he said, with 104 staffed ICU beds remaining unoccupied and ready to go Wednesday morning and 150 ICU beds occupied by patients, including those with COVID-19.

“We also have close to 400 beds that could become ICUs, so I feel like we have good headroom,” he said. “But with the new more contagious mutant variants of the virus out there, it is still concerning, and we can’t let our guard down.”

New and significantly more contagious variants of the novel coronavirus have taken hold in the United Kingdom and South Africa and are expected to eventually reach Maine. Shah said the hope is to vaccinate enough people before they do so as to stop it from spreading here. “It’s pretty clear that we’re in a race of vaccine versus variants,” he said.

There isn’t a strong correlation between new case rates at the county-level and subsequent hospitalization trends in different regions of the state, Shah said. It could be just “the law of small numbers” – the fact that in absolute terms Maine’s inpatient numbers are relatively small, so an outbreak or two can shift hospital-level trend lines by a fairly large percentage.

MaineGeneral in Augusta reported an average of 14 COVID-19 inpatients a day for the week, down from 16.3 the week before, while at Brunswick’s Mid Coast Hospital the figure was 5.9, up slightly from last week’s 5.1.

At Pen Bay Medical Center in Rockport – which has recently become another COVID-19 treatment hub for the MaineHealth hospital system – there were 7.9 inpatients each day, down from a record of 8.3 last week.

A.R. Gould, a 48-bed hospital in Presque Isle, saw the average COVID-19 inpatient count fall to 2.1 this week, down from the hospital’s record burden of 5.4 last week.

A number of other small hospitals reported having COVID-19 inpatients this week, including Sebasticook Valley Hospital in Pittsfield, Inland in Waterville, Maine Coast Hospital in Ellsworth, Stephens Memorial in Norway, and Bridgton and Rumford Hospitals.

Since the start of the pandemic, Maine Med has accumulated the heaviest COVID-19 hospitalization burden, with more than 4,600 inpatient nights of care. It is followed by EMMC (2,647), SMHC (over 1,973), MaineGeneral (1,517) and CMMC (1,280).

The pandemic eased slightly this week in the United States, with states reporting 155,629 positive tests and 4,101 deaths on Wednesday, according to The New York Times tracker, a death toll that remains substantially higher than the single-day death toll in either of the two deadliest battles of the Civil War, the Battles of Antietam and Gettysburg, or the 9/11 terrorist attacks. Maine had been one of the best performing states for much of the pandemic, but over the past month it has moved to the middle of the pack, placing 32nd among the states in terms of prevalence of the disease over the seven days ending Wednesday.

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, it is 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 Maine’s hospitals and hospital networks. The data does not include outpatients or inpatients suspected of having the virus but who were never tested. It includes most of the state’s hospitals, accounting for the nearly all of the statewide hospitalizations reported each week by the Maine CDC.