Maine reported a record 748 new cases of COVID-19 on Wednesday, surpassing the previous single-day high set last week by more than 150 cases.

Some of that increase, though, and other increases over the last week or more, are attributable to a processing backlog at the Maine Center for Disease Control and Prevention, said Dr. Nirav Shah, the agency’s director.

“Even though this increase is concerning, and it does represent a true number … it does not represent a striking increase within a 24-hour period,” he said at a media briefing, adding that other metrics, including testing positivity rate, have improved in recent days, suggesting things may have actually plateaued.

Maine has now gone over 20,000 confirmed or probable cases since the pandemic began. Half of those have come in just over a month, as the state grapples with a sustained surge at the same time vaccines are starting to be administered.

Eight additional deaths were reported Wednesday as well. So far in December, 82 people have died from COVID-19, the deadliest month so far. The overall death toll has doubled since the beginning of November and now stands at 311.

Late Wednesday, the Maine Department of Corrections reported the first Maine prisoner to die of COVID-19, an inmate in his 70s at Mountain View Correctional Facility in Charleston. Corrections officials declined to name the man or provide any other details about his case because of medical privacy. His death was not reflected in the CDC’s totals Wednesday.

A man walks along Congress Street in Portland last month.  Ben McCanna/Staff Photographer

COVID-19 hospitalizations increased to 187 individuals Wednesday, including 46 in critical care and 19 on ventilators. Since March, exactly 1,000 people have been hospitalized with the virus at some point.

Gov. Janet Mills, who joined Shah at Wednesday’s briefing, said that although the arrival of vaccines has offered a “desperately needed ray of hope,” the state is months away from breathing easy.

“The bottom line is: We in Maine are still very much in the throes of this virus, as is every state in the country,” she said. “We can, and we must, do better controlling this.”

The seven-day average of daily new cases stood at 461 on Wednesday, up from 205 one month ago and 34 two months ago. In 11 of the last 17 days, the number of cases has topped 400, including two days last week when there were 551 and 590 new cases. New cases were reported in every Maine county Wednesday, led by Cumberland County with 181, York County with 165 and Penobscot County with 90.

Maine’s average daily case number has increased 17.8 percent in the last week, the highest rate of any New England state, according to the COVID Tracking Project. New Hampshire is close behind with an increase of 16.8 percent in the last week, but its average daily case number – about 780 – is much higher.

Two Maine hospitals are dealing with major outbreaks. York Hospital reported eight new positive cases among staff on Wednesday, bring the total to 45 since the outbreak was discovered on Dec. 6. The outbreak also has spread to 13 patients there, three of whom have died. Northern Light Eastern Maine Medical Center in Bangor had a total of 48 COVID-19 cases as of Tuesday – 40 staff members and eight patients.

Dr. James Jarvis, senior physician executive for Northern Light Maine Health, said Wednesday that the recent increase in positive cases has multiple causes. More people are inside, where the virus spreads more easily. The air is drier, which means COVID-19 droplets can linger in the air longer. There has clearly been a Thanksgiving spike, coupled with college students returning home from every state. And people have been out Christmas shopping.

“The virus is prevalent,” he said. “There is a much higher likelihood of being exposed wherever you are going.”

In explaining the recent case reporting backlog, Shah said every positive case that comes into the Maine CDC needs to be verified. His agency has streamlined that process in recent days and has brought on more staff to help, which has resulted in some higher numbers being reported on certain days. He expected that to continue in the coming days as well and said higher case numbers on one or two days might not necessarily represent an alarming spike.

The positivity rate, one of the metrics that Shah noted had recently improved, was at 5.4 percent Wednesday after being as high as 6.2 percent over the last month. The statistic represents the percentage of all tests that come back positive.

Maine’s Department of Health and Human Services announced Wednesday the launch of a new text messaging service that tells people who test positive what steps they should take. Commissioner Jeanne Lambrew explained that the text alert system is a supplement to what the state already is doing, but it provides immediate information for individuals to begin quarantining and to reach out to people they may have been in contact with.

Cases, hospitalizations and deaths have soared since Thanksgiving, prompting fears that another surge is possible after the Christmas holiday, even though state and federal health officials have pleaded with Americans not to travel.

Mills and Shah both made additional pleas Wednesday for Mainers to stay home if possible.

“The biggest gift we can give each this holiday season … is the gift of health, the gift of life,” the governor said.

Shah said the most important thing for people to remember is that all gatherings outside the home are a risk.

“We should go into this week acknowledging that,” he said. “If a gathering is in your family’s cards, think about whether you can do it virtually.”

If not, Shah urged individuals to keep gatherings as small and as short as possible, keep the most vulnerable people away and wear a face covering.

Mills was asked Wednesday if she’s considering any other restrictive measures to combat further spread.

“It’s something we talk about just about every day: What are we not doing that we could be doing,” she said.

Mills didn’t announce any additional restrictions, but doubled down on urging Mainers to be vigilant through the winter so the vaccine can do its job.

Vaccines are slowly making their way across the country, providing a glimmer of hope as 2020 comes to a close. Front-line health care workers and residents and staff of long-term care facilities in Maine have started to receive either the Pfizer-BioNTech or Moderna vaccines, and additional doses are coming every week.

As of Friday, at least 8,000 vaccines had been administered. Shah also announced that one person, a health care worker at Maine Medical Center, had an allergic reaction to the vaccine but was being monitored and was doing well.

The state has launched a new online dashboard that has information about vaccines, including updates on which categories of people will be eligible for vaccinations when supply arrives. Maine placed an order Friday for an additional 10,725 doses of Pfizer’s vaccine and 8,400 doses of Moderna’s vaccine for next week.

There has been some confusion about the order in which certain groups of people should be inoculated as the state’s vaccination plan continues to evolve. An interim draft plan posted on the Maine CDC’s website in October is now partly obsolete because state health officials have since adopted the multiphase vaccination plans proposed by the U.S. Centers for Disease Control and Prevention.

For instance, the Maine CDC added residents of long-term care facilities to the first phase of its vaccination plan in response to federal guidance. In the latest adjustment, Shah indicated Monday that Maine will follow a federal advisory committee’s recommendation to include individuals age 75 or older as well as front-line “essential” workers in the next phase of vaccinations.

That means tens of thousands of teachers, police officers, correctional officers, grocery store workers and postal employees could be eligible for vaccination as early as late January or early February, if vaccine supplies and federal distributions keep pace.

Mills said on Wednesday that things have been changing rapidly with vaccines, but the state is committed to rolling out vaccinations as equitably as possible, keeping in mind risk factors for each category.

“Nothing simple about any of this,” she said. “Every person to me is essential.”