One million Mainers have received at least one shot of a COVID-19 vaccine, Gov. Janet Mills’ office announced Tuesday, but clusters of unvaccinated individuals continue to fuel regional hot spots even as case trends statewide show “signs of optimism.”

State health officials reported 897 new cases Tuesday, including 73 in Androscoggin County, 13 in Franklin County and 36 in Oxford County. Tuesday’s count represents cases from Saturday, Sunday and Monday.

The Maine Center for Disease Control and Prevention no longer reports new cases over the weekend.

There were 10 additional deaths, eight of which occurred between Sept. 11 and 25. Those were a result of the Maine CDC’s periodic review of death certifications. The deceased were residents of Aroostook, Cumberland, Kennebec, Knox, Penobscot and Piscataquis counties.

“There are some very early, way too preliminary, unclear signs that there might be an easing” of the pandemic, Maine CDC Director Dr. Nirav Shah said at a media briefing last week. “But I’m not taking that to the bank yet.”

More than 90% of Mainers 65 years and older, for example, are fully vaccinated, Shah said.

“Those are important numbers and really indicative of how well protected older Mainers are against COVID-19.”

But regional differences in vaccination rates prevent Maine from reaching population-level immunity, Shah said.

“It’s not so much the aggregate number of how many people are vaccinated. It’s where the individuals are,” he said. “Vaccination, in order to be effective at a population level, we need to have equal coverage across the state.”

Nearly 86% of Cumberland County residents 12 years and older are fully vaccinated against COVID-19, as of Tuesday, making it the most vaccinated county in the state.

At the other end of the spectrum, only 61% of eligible Somerset County residents are fully vaccinated.

“It won’t surprise anyone to hear that there’s a correlation between vaccination rates at the county level and COVID-19 (case) rates at the county level,” Shah said.

About 74% of all eligible Mainers have received their final shot, which does not include a booster shot.

In a prepared statement, Mills applauded those who “have rolled up their sleeves to turn the tide on this pandemic.”

“But as we have seen over the last several weeks, the dangerous and more infectious delta variant still presents a serious threat and has made it all the more important for Maine people to get vaccinated,” she said.

Eligible residents of Androscoggin, Franklin and Oxford counties are 67.9%, 62.4% and 63.8% fully vaccinated, respectively. The tri-county region still ranks among the least vaccinated in the state.

Oxford County’s seven-day average of new daily cases now stands higher than Androscoggin and Franklin counties’ average, as well as the state’s average.

There were 5.03 new cases of COVID-19 per 10,000 residents of Oxford County every day for the seven-days ending Tuesday. Androscoggin County’s seven-day average was 4.13 cases per 10,000 residents and Franklin County’s was 3.34 cases per 10,000 residents.

Statewide, the seven-day average was 4.45 cases per 10,000 residents.

This comes after a few weeks in which Franklin County led the region and much of the state in new cases per capita. But a precipitous drop in cases over the past week indicates trends may be easing there.

But, as Shah warned last week, “things are still unsettled. There’s still a lot going on and we’re not out of this yet.”