LEWISTON — Central Maine Medical Center and St. Mary’s Regional Medical Center have hit a record number of patients with COVID-19 for the second week in a row, while cases are flat or falling at other hospitals across the state. It is unclear why Lewiston is suddenly seeing more people acutely affected by the virus.

“There’s no real outbreak that we know of in any nursing facilities specifically or anything like that,” St. Mary’s spokesman Stephen Costello said. “We kind of racked our brains about it. There’s nothing that we can point to (and say), ‘Oh, that’s why.'”

For the six days ending Wednesday, Central Maine Medical Center cared for an average of 16.2 patients with COVID-19 each day, up from 15.6 last week and 11.1 the week before, a Portland Press Herald survey found. St. Mary’s had an average of 10.1 inpatients each day for the week ending Thursday, breaking last week’s record breaking figure of 7.4.

On Thursday, St. Mary’s had 13 COVID-19 patients. For the first time, its six-bed intensive care unit was filled exclusively with people who had COVID-19.

If more patients need the ICU while it’s full, St. Mary’s could implement its surge plan, which would shift patients to other parts of the building.

“We have kept places open in the hospital that we could expand to,” Costello said.

A CMMC spokeswoman did not return a request for details about that hospital’s increase in COVID-19 patients by deadline on Thursday.

While Lewiston’s hospitals are seeing an increase in patients, the pressure eased slightly at Portland’s hospitals, including the state’s largest. Maine Medical Center reported an average of 39.3 inpatients a day for the week ending Thursday, down slightly 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 Southern Maine Health Care Medical Center in Biddeford reporting an average of 13.6 Covid inpatients a day for the week compared to 14.4 last week and well below its record of 23.2 set in late December. York Hospital in York, a 48-bed community hospital that was hit hard by the disease a month ago, cared for an average of 2.9 Covid inpatients each day this week, down from six last week and 10.7 three weeks ago.

Northern Light Eastern Maine Medical Center in Bangor had been the busiest COVID hospital in the state for much of December but has continued to see declining demand, with 19.6 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.

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

As Lewiston’s hospitals deal with a spike in cases, they are also working on mass vaccination plans. St. Mary’s learned Thursday that it will be getting doses next week, but it could not yet say how many. Some of those shots are expected to go to the B Street Health Center in downtown Lewiston, where Maine Department of Health and Human Services Commissioner Jeanne Lambrew said officials particularly hope to vaccinate older members of the Somali community.

“That is one of many that we hope that are going to be targeted, specific efforts to go to where older Mainers are, especially those that are hard to reach,” she said during the Maine Center for Disease Control and Prevention’s regular news briefing on Thursday.

During that briefing, the CDC also announced an outbreak at the Norway Center for Health and Rehabilitation, where there are five cases.