A respiratory illness most commonly seen in winter has been responsible for nearly 500 Minnesota hospital admissions since May, adding to the capacity worries caused by a renewed surge of COVID-19 patients.

RSV, or respiratory syncytial virus, often leads to respiratory infections in young children and the elderly. It is the most common cause of bronchiolitis and pneumonia in children younger than 1.

The disease was largely dormant during the colder months, as was influenza, most likely because of masking and social distancing. But after vaccinations tamped down new COVID-19 infections, use of those safety measures waned and with it RSV re-emerged.

The state's hospitals report they are at 92% capacity, including patients with COVID-19, RSV, traumatic injuries and other medical complications.

"In our system, the majority of patients that we are seeing is not COVID," said Dr. Mark Sannes, HealthPartners senior medical director. "We are extremely busy with non-COVID issues right now and COVID is taking us to the point where we are at capacity."

Since Aug. 4, about 100 COVID-19 patients were admitted every seven days, with 584 hospitalized as of Wednesday, including 165 in intensive care.

That's still far below the nearly 1,900 COVID-19 patients in Minnesota hospitals toward the end of the large fall surge, but substantially higher than the recent low of 90 patients on July 14 — just as the most recent COVID-19 wave began.

In addition to RSV and trauma patients, hospitals are studying whether some of their recent admissions are patients who delayed getting primary care last year because of the pandemic.

The Minnesota Hospital Association said that some of its members report 30% more strokes than expected.

Like many other industries, hospitals and other health care organizations are reporting staff shortages.

This week the Minnesota Board of Nursing sent an e-mail to the state's nurses seeking volunteers to work in long-term care facilities that are facing staff shortages.

Hospitals say that some employees are leaving the field or going part-time after enduring the grueling demands of the pandemic.

"Some have chosen to retire, some are taking some much-needed time off, and others have decided to leave the health care field entirely," M Health Fairview spokeswoman Aimee Jordan said. "Staff are frustrated to be in a situation that could have been avoided if more people got vaccinated."

Hospitals pay close attention to demand and adjust staffing levels in response, sometimes sending out calls for nurses and other health care workers to pick up additional shifts.

But that is becoming more difficult with the staffing shortage amid increasing hospital census levels.

"We currently have enough physical spaces and seem to be holding steady with supplies, but staffing is the current challenge for our member hospitals and health systems," said Emily Lowther, communications director for the hospital association.

Shortly after the pandemic began in Minnesota in March 2020, Gov. Tim Walz enacted a ban on elective or less-essential surgeries in an effort to free up health care workers and personal protective equipment in preparation for COVID-19 hospitalizations.

With the pandemic emergency lifted, Walz no longer has the power to reinstate another ban, but he said that is not necessary because state and industry officials have learned how to manage the pandemic.

The hospitals are "making those decisions on their own. They've learned too, the hospitals. They've become very, very good, and they were good to begin with, but they've become very good at managing those caseloads," he said.

"The hospital space is crowded right now and that is a confluence of the delta variant and the trauma season," Walz said. "People are crashing their ATVs, they're on the road more, that's just the reality."

As of last week, 19 of the 97 hospitals that reported hospital capacity data to the federal government said they were at least 95% full.

Six reported that they were maxed out, including HCMC, Abbott Northwestern and Regions hospitals in the Twin Cities.

COVID-19 could lead to more hospital admissions as the rate of confirmed cases continues to grow.

Typically, it can take several weeks after infection for the disease to progress to a stage where hospital care is needed.

Minnesota's confirmed COVID-19 cases rose to 642,288 on Thursday after the Minnesota Department of Health announced another 1,839 new infections.

Eleven more deaths were reported, including six who lived outside the Twin Cities metro area.

So far, the pandemic has been linked to 7,793 fatalities.

At the end of June, 1.1% of Minnesotans tested positive for the virus.

That number is up to 6.1%, a sign that virus transmission levels have increased.

Most people who are hospitalized, as well as most new infections, are among those who are not fully vaccinated.

Although nearly 3.1 million Minnesotans have received the recommended doses of COVID-19 vaccines, about 45% of the state's population is not fully vaccinated. Children under 12 are not eligible for a vaccine.

There is no vaccine to protect against RSV. Health officials say that masking, social distancing and hand washing will help prevent infection. RSV can live for several hours on hard surfaces, research has found.

Patients with RSV infection typically have fever, cough, wheezing or a runny nose.

In an alert to health care providers in early August, the MDH said patients with respiratory symptoms should be tested for RSV if they tested negative for COVID-19.

It is unclear what path RSV will take in the coming weeks.

"Providers at Mayo Clinic and elsewhere across the country are seeing an increase in RSV cases and expect an extended RSV season this year," said Ginger Plumbo, a communications consultant for the Rochester-based clinic. "Mayo Clinic is prepared to handle any increase in RSV cases over the coming months."

Dr. Robert Sicoli, medical director of emergency services at Children's Minnesota, said that he has not seen so many summertime RSV cases in the 30 years he's been a physician.

The hospital was expecting some cases because there were RSV cases during the summer in the Southern Hemisphere, where viral activity can sometimes be a predictor of cases in the north.

"We began to see some significant RSV activity in June, rising through July and our levels of overall incidence and hospitalizations in August approximate what we typically see in a [winter] surge season," he said. "Hopefully we've reached the peak of the curve and we will see some declines."

Staff writers Briana Bierschbach and Christopher Snowbeck contributed to this report.

Glenn Howatt • 612-673-7192

Twitter: @GlennHowatt