Maine hospitals are preparing to administer the state’s first coronavirus vaccines to medical staff after the first doses arrived Monday, part of a massive national vaccine rollout and a first small step toward ending the pandemic.

Officials at Northern Light Health, a statewide network of hospitals, said vaccine doses were delivered Monday morning to Mercy Hospital in Portland and Eastern Maine Medical Center in Bangor. The hospital group expects to begin inoculating front-line medical workers at 6:30 a.m. Wednesday after an internal review and scheduling of staff to ensure they can be tracked after receiving the vaccine.

Health care workers in states including New York, Ohio and Rhode Island started receiving the vaccine Monday. But each hospital system around the country is handling the initial rollout to their workers independently, and some are moving more quickly than others.

“I can’t speak for other states or other health delivery systems, but Northern Light Health has consistently said that this would be our process,” Suzanne Spruce, associate vice president and chief communication officer for Northern Light, said in an email Monday. “Safety is always our top priority. The final (Advisory Committee on Immunization Practices) guidance has not yet been released and we are reviewing the interim guidance to ensure that our informed consent matches that of this guidance.

“Our internal review also includes certifying our vaccine scheduling system is ready to ensure appropriate tracking of staff receiving the vaccine. This work was underway well before the vaccine arrived, but we still have some checks and balances to complete,” Spruce said.

Each of the two Northern Light hospitals received 975 doses, part of an initial shipment of 12,675 doses of Pfizer vaccine to Maine expected this week. About half of the total number of doses will go to health care workers at the highest risk of exposure while the remainder will go to long-term care facilities through a different distribution network that includes pharmacies.

In addition to the shipments received by Northern Light on Monday, the state is expecting about another 3,900 doses to arrive by Tuesday for distribution to hospitals that include Central Maine Medical Center in Lewiston, Maine Medical Center in Portland, Maine General in Augusta,  St. Mary’s Hospital in Lewiston and AR Gould Hospital in Presque Isle. Thousands of additional doses are expected in the coming weeks, although most Mainers will likely not have access to vaccines until spring or summer.

The deliveries are reaching Maine as the virus is surging. Maine reported 426 new COVID-19 cases Monday, marking the fifth time the state has seen more than 400 cases in a single day. While news of the vaccine’s arrival marked a historic achievement and a hopeful development, officials also cautioned that the pandemic is still very much ongoing and people should not let their guards down.

“This is a real disease and the consequences are great,” said James Jarvis, senior physician executive for incident command at Northern Light. “We need the help of members of our community to continue to wear masks and face coverings when you’re out in public, to stay 6 feet apart when out in public, and to stay home when you’re not feeling well.”

The Northern Light hospitals say employees who have frequent contact with COVID-19 patients will be vaccinated first. That group includes physicians, nurses, environmental services staff, housekeeping staff and dietitians.

“Our prioritization list really is staff who have come in contact with COVID-19 patients,” Jarvis said.

Staff will have scheduled appointments to receive their vaccinations and will be vaccinated in staggered groups so an entire department does not receive the vaccination at the same time and is unable to work in the event they experience side effects.

Though hospitals cannot require employees to receive a vaccine that is under emergency use authorization, it will be strongly recommended that employees get inoculated.

The initial 1,950 vaccinations should be enough to cover health care workers at both EMMC and Mercy who have the most interactions with COVID-positive patients, Paul Bolin, senior vice president and chief human resource officer for Northern Light, said during a virtual news conference. The Pfizer vaccine requires two doses 21 days apart in order to be fully effective, and the hospitals are expecting to receive another shipment to cover the second doses for those people.

Officials with Northern Light acknowledged there have been some challenges to rolling out the vaccine, including not knowing until Friday the final quantity of vaccine they would be receiving and at what locations.

“One of the initial issues that we overcame quickly was pending info about the quantity of vaccine to be received at each location and the timing of that,” Bolin said. “(In order to) internally identify by risk which groups of employees would appropriately receive the vaccine first, it was important to know how much we would have available. We found that out late last week and put that into our plan, so we’re working quickly to administer the vaccine in that order.”

The initial Pfizer vaccine deliveries this week are going to larger hospitals with capacity to store the vaccine in ultra-cold freezers. A vaccine developed by Moderna that does not need to be kept in a deep freeze could be distributed next week and will be allocated to about 30 smaller hospitals around the state.

Jason Gould, director of marketing and business development at Covenant Health/St. Mary’s Health System, said St. Mary’s Regional Medical Center in Lewiston was awaiting delivery of roughly 500 doses of vaccine Monday afternoon. However, the hospital later said the delivery would come Tuesday.

“We are in the process of formulating a plan to distribute the vaccine when we do receive it,” Gould said.

Gould said the hospital will begin distributing the vaccine “as soon as” it arrives and in accordance with the procedures outlined by the CDC. He said that includes individuals who are likely to be exposed to infected patients or patients who are being investigated for COVID-19.

“It’s unlikely the initial distribution of vaccines will be sufficient to cover all of our staff, so we are in the process of prioritizing who needs to get it based on the CDC guidelines,” he  said.

MaineGeneral Health in Augusta also is expecting to receive its first shipment on Tuesday and begin inoculations on Wednesday.

“We anticipate receiving the COVID-19 vaccine from the state on Tuesday, Dec. 15, 2020, and we are in the planning stages to start distributing the vaccination as early as Wednesday, Dec. 16, 2020,” Dr. Steve Diaz, chief medical officer at MaineGeneral Health, said in a written statement released by a spokesperson.

Maine Medical Center in Portland, which is part of the MaineHealth network, is expecting 1,885 doses on Tuesday, said Dr. Nirav Shah, director of the Maine Center for Disease Control and Prevention.

“We have been planning for weeks now and we are very ready to receive and distribute the vaccine,” MaineHealth spokesman John Porter said.

MaineHealth, which operates nine hospital systems in the state, including Maine Med, said on Friday that it will give its initial allotment of the vaccine to the direct care providers at its hospitals that have seen the highest number of COVID-19 patients. Porter said that includes Maine Med, Southern Maine Health Care and Mid Coast-Parkview Health.

MaineHealth also said the initial vaccinations will be directed to intensive care unit teams, emergency department caregivers, those providing care in dedicated COVID-19 inpatient units, and other critical and essential inpatient services that are not available elsewhere.