Maine added a near-record number of COVID-19 cases on Wednesday even as state health officials noted that other, closely tracked indicators offered “signs of optimism” that the current surge is easing.

The 867 cases reported Wednesday represented the second-largest one-day jump and were exceeded only by the 1,008 cases reported Tuesday for the previous three days. The last time the Maine Center for Disease Control and Prevention reported more than 800 cases in a single day was in mid-January during the worst surge of the now 18-month-long pandemic.

No COVID-related deaths were reported Wednesday.

Daily case numbers appear likely to remain high in the coming days as the Maine CDC staff reviews roughly 2,500 positive test results reported to the agency over the past week. While that backlog has no impact on when patients learn of a positive test result – because most are notified immediately by the lab or their doctor – it affects the closely watched daily tally of case numbers.

Dr. Nirav Shah, director of the Maine CDC, said 13 additional staff members have been added since last week to the team that reviews positive test results to distinguish new cases from duplicates. Additionally, Shah noted that the number of positive cases arriving daily for vetting ebbed slightly from well over 600 a day last week to about 550 daily as of Wednesday.

But Shah said case numbers are only one metric his team uses “to understand how things are unfolding in real time.” Perhaps the best indicator, Shah said, is the positivity rate, which is the percentage of total tests that come back as positive. Maine’s seven-day positivity rate dipped to 4.6 percent on Wednesday from 6.1 percent two weeks ago. Maine’s testing rate also has increased 19 percent over the past two weeks.

Hospitalizations ticked up from 218 on Tuesday to 225 on Wednesday but are lower than the record 235 patients that were in the hospital with COVID-19 on Saturday. There were 71 people in critical care beds and 31 connected to ventilators on Wednesday.

NorDx Laboratories started processing coronavirus tests in March 2020. The Maine CDC is now facing a backlog of roughly 2,500 positive test results reported over the past week. Brianna Soukup/Staff Photographer

Always reluctant to give “crystal ball” predictions about the pandemic in Maine, Shah gave a characteristically cautious assessment as he noted “some signs of optimism on the horizon – but there are still a lot of signs of concern.”

“When you take all of that together there are some very early, way-too-preliminary, unclear signs that there might be an easing,” Shah said during a Wednesday briefing with the media. “But I’m not taking that to the bank yet.”

Dr. James Jarvis, the COVID-19 incident commander for Northern Light Health, which operates Eastern Maine Medical Center in Bangor and other hospitals around the state, also hopes that the delta-driven surge is easing.

“It looks like the state of Maine is kind of at a plateau but at a plateau at one of the highest (levels) of numbers that we have seen during this entire pandemic, including last winter when … we were hopeful that was going to be the worst that we saw,” Jarvis said in a separate briefing with reporters. “I do hope that, as we’ve seen in other parts of the country, that numbers will start to decrease over the next few weeks. That is a hope and that is not a forecast.”

Maine has among the highest vaccination rates in the nation and has consistently reported among the lowest COVID-19 case and death rates throughout the pandemic. Yet the state’s seven-day case rate of 271.9 cases per 100,000 residents was the highest in New England on Wednesday and was higher than every other Northeastern and mid-Atlantic state except Delaware, according to the latest data from the U.S. CDC.

The seven-day average of new cases of COVID-19 stood at 559 on Wednesday, up from 456 cases per day for the week ending Sept. 15. The highest-ever seven-day average of just over 600 COVID-19 cases occurred in mid-January, but Maine was averaging just a few dozen cases a day in early July.

To date, the Maine CDC has tracked 89,064 confirmed or probable cases of COVID-19 since the coronavirus was first detected in the state in March 2020. There have been at least 1,022 deaths linked to COVID-19 in Maine during the pandemic.

The latest surge has been driven largely by infections among unvaccinated individuals with the more contagious delta variant, which accounted for 99 percent of all cases in the Maine CDC’s most recent report on the genetic sequencing of COVID-19 cases.

As of Tuesday night, 73.6 of all eligible Mainers and 64.8 percent of the state’s 1.3 million residents had received the full regimen of doses needed for full inoculation against COVID-19. But vaccination rates vary widely across the state, ranging from more than 85 percent of eligible Cumberland County residents being fully vaccinated to just 60 percent in rural Somerset County.

While there had been roughly 2,700 so-called “breakthrough” infections among fully vaccinated individuals as of Sept. 24, the vast majority of new cases in Maine as well as 65 to 75 percent of all hospitalizations have been among the state’s smaller pool of unvaccinated individuals.

Medical studies show that fully vaccinated people are much less likely to require hospitalization or die from COVID-19 than their unvaccinated counterparts. Even so, the number of fully vaccinated individuals requiring hospitalization or critical care has risen in recent days.

As of Tuesday, fully vaccinated individuals accounted for nine of the 31 people in critical care beds at Eastern Maine Medical Center and other intensive care units operated by Northern Light Health. One-third of all COVID-related hospitalizations within Northern Light’s network were fully vaccinated patients.

Asked about the serious cases among vaccinated individuals, Shah said numbers fluctuate but that breakthrough cases are inevitable because vaccines help prevent serious illness and death, not necessarily infection. Federal regulators have recommended a third or “booster” shot for people vaccinated with Pfizer because of studies showing that protection from the vaccine may wane over time.

“In a state with only, hypothetically, 10 percent of the population vaccinated, there wouldn’t be that many breakthrough cases,” Shah said. “We are the third most vaccinated state in the country and, as a result of that, we may see more breakthrough cases.”

Jarvis said “the overwhelming majority” of people requiring hospitalization have been unvaccinated even though they account for a minority – roughly 26 percent – of the state’s eligible population.

“The vaccine is still clearly the best way out of this pandemic,” Jarvis said during the Northern Light news conference.

There have been 16,520 additional or “booster” shots administered in Maine, according to state CDC data. Of those, roughly 6,500 have received Pfizer booster shots since federal regulators announced the guidelines last week.

Health care providers and pharmacies in Maine have started scheduling appointments to administer third doses of the Pfizer vaccine to individuals who received it initially and qualify for the booster shots. Those include individuals who are 65 or older, younger people with underlying medical conditions, and people who work in health care, as teachers, in day care facilities, in grocery stores or in other settings with higher risk of occupational exposure to the virus.

Based on federal guidelines, booster shots can be administered to eligible individuals starting six months after their second Pfizer shot. Additionally, federal regulators had previously authorized booster shots for individuals with severely compromised immune systems – such as organ transplant recipients and cancer patients – as long as they were vaccinated with either the Pfizer or Moderna drugs.

Federal regulators are still reviewing the medical data about more widespread booster shots for individuals who received either the Moderna or Johnson & Johnson vaccines.