(CNN) First, it was a smaller hospital with fewer than 200 beds in Farmington, New Mexico, where the high desert borders the Navajo Nation. Then, it was a massive university hospital in bustling Salt Lake City, Utah, with about 800 staffed beds.
The devastating effect that the Covid-19 pandemic has had on life-saving care, the well-being of front-line workers and health systems as a whole could be felt in both places, said US Navy Lt. James Kirlin, a registered nurse who has been deployed to help support them during the pandemic.
Since the early days of the health crisis -- when there was no vaccine against Covid-19 and some hospitals ran out of health care workers -- military medical personnel have been deployed to assist overwhelmed medical facilities across the United States.
Now -- with more than 65% of the US population fully vaccinated and Covid-19 hospitalizations dropping near their lowest point ever -- the final Department of Defense military medical team responding to the Covid-19 crisis ends its clinical mission Tuesday.
"It's hugely momentous, and I think this has been the largest domestic deployment of federal medical personnel in our history," said Natalie Quillian, the White House's deputy coordinator of the Covid-19 response.
Kirlin's team, about 25 personnel, was deployed to Salt Lake City on March 5 to support the University of Utah Hospital's staff and patients. The hospital is planning a special "clap out" for the team members on Wednesday.
This week will mark the first time since 2020 that no military medical personnel remain deployed on a Covid-19 clinical mission. In that time, nearly 5,000 federal personnel have been deployed across 49 states and territories to help, according to the White House.
These far-reaching medical deployments were the first of their kind in response to a public health emergency, according to Col. Martin O'Donnell, a spokesperson for US Army North.
"We've seen it for other responses -- like hurricanes, like wildfires -- but not for a public health emergency, not for a pandemic," O'Donnell said. "It's unique in that sense. Not unique in the fact that we've never worked in support of a lead federal agency or have never provided support in the homeland but unique in the sense that it's a public health emergency of this size and scale."
Hospital patients and visitors alike probably assumed that Kirlin, 38, and his fellow military personnel were part of the usual hospital staff. In emergency rooms, they cared for serious cases -- pediatric car crash victims and patients overdue for surgery -- just like any other staffers would.
"I am literally almost indiscernible from any of the other staff at these facilities. I work the exact same shifts," Kirlin said Monday night, just hours before starting his 12-hour shift -- from 7 p.m. to 7 a.m. -- at the University of Utah Hospital.
"Being part of this team that's remaining in the fight to help our country battle this problem that we've been facing the last few years, for me, it's been a very rewarding experience."
The first military medical personnel to respond to the Covid-19 pandemic arrived in New York City in spring 2020. The US military set up temporary medical centers to treat people ill with the coronavirus.
"As things progressed, as we coordinated with the lead federal agency, local medical care providers and administrators as well as other partners, we realized that perhaps the alternate care centers aren't the way to go," O'Donnell said. "We realized probably the best way that we can support is integrating within the hospitals."
As the pandemic grew, medical personnel from military treatment facilities across the country were deployed to states to support hospitals that were overwhelmed with patients and short on staff.
"The support teams were placed after surge levels reached peak in communities of highest burden -- so they really were not a precursor of a public health emergency as much as another indicator that community burden was at a high level in the health care settings," Lori Tremmel Freeman, chief executive officer of the National Association of County and City Health Officials, wrote in an email Monday.
Then, with the rollout of coronavirus vaccines, military medical personnel were deployed to help with administering shots and other pandemic response efforts.
President Biden "made a decision, during the transition, once he got into office, to deploy the military to help run some of our mass vaccination sites that were really critical for those first 100 days in getting shots into arms," Quillian said. "It was the first time we had deployed them for a mission like this domestically."
In addition to vaccinations, military members were deployed nationwide to help with responses in hard-hit communities during the Delta and Omicron surges.
Quillian said that the process to deploy these teams involves federal agencies -- the US Department of Health and Human Services, the Federal Emergency Management Agency and the Department of Defense -- receiving requests for support from governors. FEMA assigns a mission for HHS or DoD teams to deploy, based on those requests.
"At this point, we don't have requests coming in for our teams, and so we're able to draw down the last team," Quillian said. "I should add that we stand ready if we saw another surge."
At the University of Utah Hospital, that last Navy medical team helped respond to staffing shortages, opening hospital beds and rescheduling surgical procedures that were put on hold during the most recent Covid-19 surge.
"When we come into these hospitals, they really utilize us to the full scope of our practice, and we are full contributing members to their health care team," Kirlin said. The military personnel provide support to the hospital doctors, nurses and other staff members who have worked nonstop for two years, through the emotional and physical toll of the pandemic.
"These hospitals don't need help with just Covid. They need help with everything that Covid has done to their facilities," Kirlin said. "I don't think it's a secret that there's a nursing staffing shortage in this country right now, and doctor shortages. The things that Covid has overtaken over the last two years are things like cancer screenings, elective surgeries."
In the three weeks since the Navy's Clinical Recovery Team arrived in Utah, "we have been able to clear approximately 25% of our surgical backlog," Dr. Kencee Graves, the hospital's associate chief medical officer for inpatient care, who helped oversee and coordinate the military deployment, wrote in an email Monday.
"The Navy team allowed our faculty and staff to have their planned days off actually off, rather than being called into work," she added.
Now, as Covid-19 cases, hospitalizations and deaths trend down in Utah and across the country, "University of Utah Health is working hard to address some of the indirect effects of the COVID-19 pandemic, such as the delayed surgeries," Graves wrote.
"We continue to monitor the status of the COVID-19 pandemic in other parts of the world to allow us to respond as quickly as we can should we see another surge. I think we all remain hopeful that COVID-19 will be under control moving forward; and in healthcare we will be better prepared if we remain proactive and flexible with our plans."
For about two-thirds of the military medical team that's ending its Covid-19 assignment in Utah this week, the deployment was their first mission to support a civilian hospital, according to the White House.
The other third of the team provided support in Farmington, New Mexico, in January and February.
"I would see things in the emergency room in New Mexico that in my normal job in the military, I'm just not exposed to as much," Kirlin said. "Unfortunately, I had a couple of very serious automobile accidents that involved pediatric patients, and that's always challenging to deal with."
In those dark times of trauma and death, Kirlin said that getting to know and care for the broader community was "emotionally rewarding" and provided rays of hope. He connected with many of his patients from the nearby Navajo Nation, which was among the communities that Covid-19 hit hardest in the United States.
Kirlin said he met patients who could count five to 10 people whom they knew personally who died of Covid-19.
"Their experiences over these last two years have been nothing short of traumatic, and to just be a small part of being able to provide some relief to these communities, for me, that was the most gratifying experience," he said.
Kirlin's story seems to mirror many deployments across the country.
"My sense is that they were very important during the surge and in some jurisdictions they helped prevent the medical system from being overwhelmed," Dr. Marcus Plescia, chief medical officer at the Association of State Territorial Health Officials, wrote in an email about the deployment of military medical teams in general.
"It's not unreasonable to scale back right now, and we are certainly better able to manage COVID now with vaccines and therapeutics," Plescia wrote, adding that this scaling back does not necessarily mean the pandemic is over.
"We don't know what the future may bring," he said. "And it's important not to be complacent, especially after we have made so much progress."
Freeman, of the National Association of County and City Health Officials, agreed that we're not done with Covid-19.
"During the Alpha, Delta and Omicron waves of the pandemic these teams were absolutely necessary to help relieve hospitals and health care staff," she wrote. "The country, in the name of public health preparedness and response, needs to be prepared to return to successful tactics from the past if we enter another period involving another variant should it have a deleterious effect on local communities' ability to treat patients seeking health care for COVID."
When it comes to the future, Kirlin said, there are "a lot of unknowns."
Now that his deployment has ended, he travels home Wednesday to Poulsbo, Washington, where he can recuperate before starting a mission in Djibouti in July.
But he believes that America's fight against the coronavirus is not over.
"It's reasonable to say that we still have a long road ahead of us," Kirlin said.
"Unfortunately, the enemy, which in this case is Covid, gets a say in this," he said. "So I think we understand that the work is never truly done and that there's more work to be done -- and at a moment's notice, when our country needs our help, we're here, and we're ready to go."