MaineHealth, the state’s largest health care network, said Tuesday that it will require all employees to be vaccinated against COVID-19 by Oct. 1, announcing the mandate as virus case counts continue to increase in Maine.

“The vaccines are very effective, and are preventing hospitalizations and health complications with COVID-19. In addition, the vaccines are proven safe – we have a full year of data from the clinical trials and almost 200 million Americans have received a COVID-19 vaccination,” Dr. Dora Anne Mills, chief health improvement officer of MaineHealth, said in a written statement. “To be consistent with our values and to protect our colleagues, families, patients and communities, we believe it is paramount that all care team members be vaccinated.”

Mills said 83.8 percent of staff already have received their immunizations. MaineHealth, the parent organization of Maine Medical Center in Portland, has 23,000 employees in nine hospitals, a behavioral health system, diagnostic labs and home health agencies.

MaineHealth joins a growing list of providers that are requiring staff vaccinations. Northern Light Health, which includes Eastern Maine Medical Center in Bangor and Mercy Hospital in Portland, said Monday that it would require vaccinations for all staff as soon as the U.S. Food and Drug Administration gives full approval to one or more vaccines. Millinocket Hospital became the first Maine hospital to require staff vaccinations when it announced its policy, also predicated on FDA approval of a vaccine, last week.

MaineHealth has 23,000 employees in nine hospitals, including Maine Medical Center in Portland, a behavioral health system, diagnostic labs and home health agencies. Derek Davis/Staff Photographer

MaineHealth did not condition its vaccination requirement on full FDA approval of the vaccines. The network said it would consider medical and religious exemptions to the requirement.

Mills said in an interview with the Press Herald on Tuesday that since clinical trials and real-world usage have proven that the vaccines are overwhelmingly safe and effective, MaineHealth decided to mandate the vaccine regardless of full FDA approval. The FDA may grant full approval by late summer or early fall, but the exact timetable is unknown. Some hospital systems in other states are forging ahead with vaccine mandates and not waiting for full FDA approval as virus cases surge.

“We feel very confident in the safety and efficacy of the vaccines,” Mills said. She said the more contagious delta variant also is spurring action. “We need to act now to make sure patients and employees are protected.”

Mills said a mandate is effective, as shown by a 2020 requirement for MaineHealth employees to get a flu shot, which was followed by a state flu shot mandate this year for all health care workers.

“We lost very few employees when we implemented the flu shot mandate. What happens is people get vaccinated,” Mills said.

Steven Michaud, president of the Maine Hospital Association, said in a statement that “we fully support Millinocket, Northern Light and MaineHealth moving in this direction.”

“There will be many more to follow. MHA is actively discussing a statewide policy in this regard and will have something to say very soon. While we do not relish imposing on our unvaccinated employees, the health and safety of our patients trumps all other concerns,” Michaud said. “We cannot have patients coming through our doors expecting to be healed and coming out with COVID. It’s simply unacceptable.”

The Maine State Nurses Association, a union that represents nurses at Maine Med and EMMC, released a statement on Tuesday that said “we strongly believe all eligible people should be vaccinated, while respecting the need for medical and religious accommodations.”

According to a survey published July 30 by The COVID States Project, which is a consortium of universities including Harvard, Northeastern and Rutgers, 66 percent of Maine residents surveyed support mandatory COVID-19 vaccinations, nearly the same as nationwide approval of 64 percent.

Major employers outside of health care also are starting to mandate COVID-19 vaccinations for employment, including Walmart, Disney, Facebook, Google and Tyson Foods. In Maine, the University of Maine System is requiring vaccinations for students and staff once full FDA approval is granted. Several of the state’s private colleges and universities also have established vaccination requirements for students and staff.

Also, some restaurants in Maine are starting to require vaccination for indoor dining, including Little Giant on Danforth Street in Portland, the Portland Hunt & Alpine Club on Market Street and Crown Jewel on Great Diamond Island.

Meanwhile, Maine reported 255 new COVID-19 cases on Tuesday, a summary of new infections that were detected over the last three days. There were no additional deaths.

The Maine Center for Disease Control and Prevention does not report case numbers over the weekend, so Tuesday’s totals reflect cases reported on Saturday, Sunday and Monday.

The new case numbers reflect rising rates of infection in York, Somerset, Penobscot and Lincoln counties, enough to put those counties into the “substantial” transmission category where the U.S. Centers for Disease Control and Prevention recommends mask wearing indoors for all people. Waldo County remains in the “high” transmission category, where mask wearing also is recommended.

Although the Maine CDC has adopted the federal mask-wearing recommendation, the agency’s director, Dr. Nirav Shah, has indicated the state may reconsider its support for the federal mask-wearing guidelines because the transmission level designations change so quickly, confusing the public.

Shah said on Maine Public’s “Maine Calling” show on Monday that the system “whipsaws people.”

The seven-day average of daily new cases climbed to 93.9 on Tuesday, compared to 64.7 a week ago and 20.7 a month ago. Since the pandemic began, Maine has recorded 70,718 cases of COVID-19, and 900 deaths.

Maine hospitals reported 42 inpatients with COVID-19 on Tuesday, including 20 in critical care beds.