Residents of 100 State Street, a housing complex in Portland for seniors where a COVID-19 outbreak occurred, wait to be tested Wednesday. Derek Davis/Staff Photographer

The number of new cases of COVID-19 has risen steeply for much of the past month in Cumberland and Androscoggin counties, raising concerns that a resurgence of the disease is underway as Maine loosens the lockdown intended to slow its spread.

The renewed growth of the disease has been particularly sharp in Androscoggin County, where the seven-day moving average of new cases has risen steadily from 0.9 a day on April 28 to 13.7 on Friday, a 15-fold increase in less than four weeks.

The case trend in Cumberland County has risen steadily since April 21, from 7.9 cases a day to 24.3 on Friday, a tripling over a month.

In both counties, the upward trend began weeks before the recent spike in testing made possible by the Maine Center for Disease Control and Prevention’s partnership with Idexx Laboratories of Westbrook. They also began before Gov. Janet Mills began loosening the lockdown in those counties May 1, when hair salons, barbers, doctors’ offices and car dealerships were allowed to resume operations.

Reached Friday afternoon, Maine CDC director Dr. Nirav Shah agreed that the trends in the two counties are worrisome and that the case increases probably preceded the recent increase in testing.

“I’m not reassured. I’m concerned,” Shah said. “The risk is really high.”

After reviewing the case curves for the two counties for the Press Herald, Dr. Jennifer Nuzzo, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health had this reaction: “That’s not good.”

Nuzzo said the Androscoggin upsurge in particular is “a significant development” calling for expanded testing to get ahead of the disease before any further reopening measures are contemplated.

“I would want to feel really certain that they are testing enough to catch all the cases that are out there and particularly in these congregant settings,” Nuzzo said. “In nursing homes and long-term care facilities they probably want to do some regular testing.”

Dr. Thomas Tsai of the Harvard T.H. Chan School of Public Health said the situation in Androscoggin County calls for wide-scale surveillance testing and contact tracing. “With a large immigrant community it is important to do outreach and make sure that there is enough access to the health care system and the public health system and to make sure that we are doing active surveillance in immigrant communities that may be underserved.”

Under Mills’s reopening plan, on June 1 restaurants in Androscoggin, Cumberland, York and Penobscot counties will be allowed to reopen their dining rooms, most retail stores can open, and the limit on gatherings will increase from 10 to 50 people.

At Friday’s briefing on COVID-19 cases, the governor was asked about the wisdom of increasing the cap on gatherings. In response, she emphasized that participants would still be expected to wear masks and practice good hygiene and that the state would monitor developments closely. “It’s part of the gradual reopening effort, and we watch each day how things change,” she said.

Tsai, however, said it is unwise to consider further reopening while the state is seeing a sustained increase in cases.

“I think it’s important to treat this data like a circuit breaker on the phased reopening,” he said. “We are clearly seeing a signal that the number of cases are rising, and the appropriate response then is to take a step back and say: ‘How can we get control of this infection now in this phase before proceeding to the next phase?’”

Asked about the wisdom of going ahead with the June 1 reopenings, Shah said: “Every single time we talk to the governor, we keep every one of these trends top of mind, and they have not gone unnoticed.”

Shah said his investigators and contact tracers had found distinct situations in Cumberland and Androscoggin counties. Most of Cumberland County’s cases have been linked to outbreaks in congregate settings, such as those at Tyson Foods and Bristol Seafood in Portland and Cape Memory Care in Cape Elizabeth. In Androscoggin County, a large amount of the transmission is happening within households.

“The danger is the same, but the strategies for intervention are different,” he said.

After five weeks of flat or declining COVID-19 hospitalizations across the state, Portland’s largest hospitals also experienced marked increases over the past week, although Central Maine Medical Center in Lewiston did not. Hospitalizations are a lagging indicator, typically occurring a couple of weeks after a person becomes infected with the coronavirus.

York County has also seen an increase in daily cases over the past month, though not as steep or sustained as its northerly neighbors. The seven-day trend grew from a low of 2.1 new cases a day April 30 to 6.6 a day on May 10, but then dropped gently to 4.9 on May 17. It has since climbed to reach 7.1 new cases a day on Friday. The timing of the second pulse suggests it could be connected to an increase in testing, but the Maine CDC is unable to provide county-level data on how many tests have been conducted and what proportion have come back positive.

Shah said York County still worries him because of its proximity to southern New Hampshire and eastern Massachusetts, where the prevalence of the disease is much higher than anywhere in Maine.

“I’m still deeply concerned about York, because in community transmission settings the potential for exponential growth is still there,” he said. “I’m not predicting that York will be the next Boston, but the potential is there after you get above a certain threshold.”

Maine’s other 13 counties did not show worrying trends as of Friday, including Penobscot, which along with the three southern Maine counties is categorized as having community transmission taking place. Penobscot’s seven-day average for new daily cases peaked May 3 at 4.4 and hasn’t exceeded 1 per day since May 8.

Penobscot will be considered to no longer have community transmission taking place once it goes two full incubation cycles – 28 days – without a new case. It had three new cases Thursday, so it will still be a long wait before this change in status comes in the best of scenarios.