PORTLAND, Maine (AP) — The number of COVID-19 patients in hospital intensive care units reached alarming levels as Maine raced to vaccinate residents — surpassing a threshold of 50% of eligible Mainers being vaccinated on Friday.

More contagious COVID-19 variants are likely playing a role in the growing number of patients in ICU beds, officials said.

Central Maine Medical Center in Lewiston has been experiencing its heaviest COVID-19 inpatient burden in recent weeks. Sixteen of the 21 patients, or more than three-quarters, were in the ICU as of Wednesday, the Portland Press Herald reported.

“It’s a frightening shift. It’s not even subtle,” said Dr. Al Teng, chief of critical care at CMMC’s parent, Central Maine Healthcare. “Patients who were critically ill in previous COVID waves were in their 60s, 70s and 80s, but now we’re seeing them in their 20s. It’s quite a stark progression.”

A similar situation is happening at MaineHealth, the state’s largest hospital network and parent of Maine Medical Center in Portland. During the winter surge, about 3 in 10 of its patients hospitalized with COVID-19 required intensive care, but the proportion is now at least 6 in 10, said Dr. Joan Boomsma, chief medical officer.

There was a similar shift at Northern Light Health, the state’s second largest hospital network, with nearly half of all patients admitted to Eastern Maine Medical Center in Bangor requiring ventilators, said Dr. James Jarvis, the network’s physician incident commander.

The disturbing trend has emerged even as the state races to vaccinate. As of Friday, more than half of Mainers aged 16 and older were fully vaccinated.

“I am proud to report that more than half of Maine people have received their final dose of a vaccine — but there is more work to do to get this pandemic behind us," Gov. Janet Mills said Friday.

While some states are returning unused vaccine doses, Maine is not scaling back its vaccination efforts. All told, more than 1.2 million doses have been administered in Maine.

“Maine has placed orders for the maximum number of doses each week since COVID-19 vaccines first became available. We plan to continue doing so,” said Robert Long, spokesperson for the Maine Center for Disease Control and Prevention.

In other pandemic-related news:

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THE NUMBERS

The seven-day rolling average of daily new cases in Maine did not increase over the past two weeks, going from 416 new cases per day on April 21 to 319 new cases per day on May 5.

The Maine Center for Disease Control and Prevention reported an additional 288 infections and one death on Friday. The agency has reported more than 63,000 cases of the virus and 794 deaths since the start of the pandemic.

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ORGANIC FAIR

Maine’s annual celebration of organic farming and rural living will take place this year.

The coronavirus pandemic canceled the Common Ground Country Fair last year. Organizers said they’re planning to hold the event in its traditional home of Unity in late September this year.

Maine Organic Farmers and Gardeners Association, which organizes the event, said new safety measures will be in place because of the virus. That will include “managing attendance to reduce congestion, masks for all participants, touchless payment systems where possible, additional spacing between vendors to allow for social distancing and increased sanitation in high-touch areas,” organizers said in an e-mail.

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SCHOOLS

Androscoggin County continues to be rated as “yellow” under the state's updated color-coded health advisory.

The county that's home to Lewiston and Auburn continues to have an elevated new case rate of 77 cases per 10,000 residents, more than double the statewide average.

All other counties are green, including Kennebec, Oxford, and Somerset counties, where new infections have declined by at least 20%.

A yellow categorization calls for schools to implement extra precautions while green means the risk of COVID-19 spread is relatively low and that schools may consider in-person instruction.