One month after celebrating zero COVID-19 patients — cheering when the news was announced — the caregivers on South Seven at North Memorial Health Hospital were back battling the pandemic.

On this April morning, physical therapist Panagiotes Nelson-Nikolaides knelt on the bed behind one patient and encouraged him to practice sitting to exercise his core muscles. A cough erupted as the man straightened up.

"Good, that was nice," the therapist said. "Does it hurt? No? OK. One more time."

Three doors down inside the Robbinsdale hospital, a team of nurses had just flipped a COVID-19 patient from back to stomach to prevent clogging in his lungs. Respiratory therapists down the hall prepared to intubate a man who was bound for placement on a heart-lung bypass machine because he struggled to breathe.

Minnesota's third COVID-19 wave this spring looked very much like the first and second waves from the perspective of this intensive care unit — with a key difference. No patients were older than 70. The man groaning in physical therapy and the man struggling to breathe were in their 40s.

Statewide, the median age of COVID-19 hospital admissions has dropped from 69 to 57 — an apparent testament to the effectiveness of vaccine prioritized for senior citizens, but a reminder of the severity of the pandemic, even for younger adults.

"There was this thought that, 'Oh, it's the people that are 65 and older,' and people under 65, if they would develop COVID, it wouldn't be as much of a problem or as much of a big deal," said Kris Ehresmann, state infectious disease director. "But we are seeing serious illness in those younger age groups."

Federal tracking showed that patients 70 or older made up almost half of the roughly 1,700 confirmed COVID-19 admissions to Minnesota hospitals during the week ending Nov. 18, one of the most severe during the pandemic. Of the 702 admissions in the week ending April 14 — a lower peak in the latest wave — only 24% were 70 or older.

More infectious variants of the SARS-CoV-2 coronavirus have fueled the third wave, prompting a resurgence in COVID-19 hospitalizations from a low of 210 on March 6 to 699 on April 14.

Hospitals in Minnesota were almost as full in early April as they were during the most severe weeks of the pandemic last fall. That was due in part to a continuation of care for non-COVID patients, though, rather than the scaling back of nonessential surgeries and treatments that occurred during the 2020 waves.

"We have adequate PPE supply now" of masks and gowns to protect hospital workers, said Dr. Carolyn Ogland, North Memorial's chief medical officer. "There's also concern that if you delay [non-COVID] care, too, that that's a problem for patients. So it's that balance."

Fewer of the hospitalized patients in this wave need prolonged intensive care or placement on ventilators to breathe, she added. On April 20, North Memorial and Maple Grove Hospital combined to treat 52 inpatient cases of COVID-19. Just six were on ventilators.

When patients do end up in intensive care, though, nurses and other caregivers on South Seven say they are in rough shape — often with obesity or other conditions that compound their illnesses.

"Patients seem sicker now than they did before," said Kristi Kline, a veteran critical care nurse at North Memorial. "It seems like they're sicker faster."

Morning rounds underscored that concern on South Seven, which had 13 total patients on April 20. Among the eight with COVID-19, three were in their 60s, four were in their 40s, and one was in the 30s age range.

The rise in hospitalizations hasn't been followed by a comparable rise in COVID-19 deaths.

Allina Health reported a decline in the age of COVID-19 patients and a drop in mortality from 9.5% late last year to 2.4% in April.

HealthPartners observed similar progress — with many younger hospitalized patients still needing oxygen support to breathe but not intensive care, said Dr. Mark Sannes, a co-leader of HealthPartner's COVID-19 response. "This group at baseline has a little more reserve, probably because they're younger."

On the other hand, Hennepin Healthcare has placed four COVID-19 patients younger than 40 on heart-lung bypass machines in recent weeks to maintain oxygen flow while they fight complications from the viral infection — often because their own immune systems are overreacting.

"These people would die if we don't intervene. Its just terrifying as a 43-year-old," said Dr. Matthew Prekker, an emergency and critical care specialist at Hennepin Healthcare.

Health officials believe the declining death rate is partly because 86% of senior citizens in the state have received at least a first dose of COVID-19 vaccine.

Prekker co-authored a study released Wednesday by the CDC showing a 94% reduction in hospitalizations for fully vaccinated seniors who had received either the Moderna or Pfizer doses, the first to receive emergency approval in the United States.

Improved treatment has helped, too. Dr. Deanna Diebold, a respiratory care specialist at North Memorial, said it is clearer one year into the pandemic which therapies work, such as timely steroids to confront the immune system overreaction.

Few vaccinated people have been hospitalized because of COVID, she said.

"We did have one older woman, 77 years old, who looked like she was going to be bad," Diebold said. "She had received one dose of the vaccine. She did way better than she would have otherwise, so we have hope."

Experience with hundreds of COVID-19 patients has helped, said Kline, the veteran nurse on South Seven. Little changes in oxygen saturation or blood tests or even the sound of breathing mean something now compared to the start of the pandemic.

"You almost get a sixth sense after a while," she said.

The progress has taken a toll, though, particularly as doctors and nurses confront more patients their own age.

It was only noon on a recent April day on South Seven, and the nurses had completed two emergency intubations and three rotations of patients.

Nurse Meghan Beveridge stood in the middle of the nursing station, arms folded and looking down when fellow nurse Jen Curtis put her arm around her and offered encouragement.

"This roller coaster has taught me that it is those little moments," Beveridge said, "that are getting me through this."

Jeremy Olson • 612-673-7744