COVID-19 cases filled 53 intensive-care beds in Minnesota on Sunday, a slight increase from earlier this summer but a sign of little change in pandemic severity in the state.

ICU usage has been perhaps the most telling metric in the pandemic — with COVID-19 cases filling 399 of those beds at the peak of the winter 2020 pandemic wave and 374 last winter. But since March 4, the number has ranged between 20 and 60, according to the latest pandemic data released Thursday by the Minnesota Department of Health.

COVID-19 as the cause of hospitalizations also appears down. Among five infected patients in intensive care at HealthPartners hospitals, four were primarily there for other medical problems, said Dr. Mark Sannes, an infectious disease specialist for the Bloomington-based health system.

During pandemic peaks, "that would only happen about 2% of the time," Sannes said. "Right now, we're seeing between 50% and 75% of our hospitalized patients with positive COVID tests who are in with something else."

Much of Minnesota's COVID-19 response strategy — from lockdown measures in 2020 to vaccine incentives in 2021 — was built around preserving ICU capacity, adding importance to the statistic. But it isn't the only metric this week to show the persistent lack of change in COVID-19 activity in Minnesota.

The seven-day average of new infections increased slightly after the July 4 holiday weekend, when travels allowed for more viral spread, but has since leveled off at about 1,400 per day in August. The case count only includes infections verified by clinics and testing centers because the results of home tests are not reported publicly.

The rate of COVID-19 deaths in Minnesota similarly rose to about six per day in late July and early August but has since declined to about four per day. Of the 74 COVID-19 deaths identified so far in August in Minnesota, 67 have involved seniors. The state's COVID-19 death toll is now 13,078.

Health officials are concerned about the return of fall school classes, which in the past two years coincided with increases in the spread of COVID-19. However, forward-looking indicators of pandemic activity offer no clear direction.

Mayo Clinic's 14-day forecast suggests the state's rate of 26 new infections per day per 100,000 people could decline to 23 — but with an error margin suggesting it could actually increase to 34 or drop to 17.

Sewage sampling at more than 40 wastewater treatment plants across the state showed no consistent trend in the amount of viral material identified, according to tracking by the University of Minnesota. Viral levels in wastewater had been increasing in northeastern Minnesota but have since receded, while low levels in southeastern Minnesota have slightly increased.

Sannes said the presence of even incidental COVID-19 in hospitalized patients means the virus is still prevalent and could pose a threat in the fall and winter again — especially if it combines with what could be a worse influenza season.

"What we're seeing right now doesn't look too bad, but we've had to shift fairly quickly in the last couple years," he said.

Minnesota is nearing 4 million people who have received at least a first dose of COVID-19 vaccine, but breakthrough data shows that the best protection from severe outcomes occurs with booster doses.

While the level of protectiveness has declined since last winter, unvaccinated seniors still were more than twice as likely to die of COVID-19 in the past 60 days than fully vaccinated people, according to state breakthrough data. They were almost five times as likely to die as seniors who had also received boosters.

Vaccine- and infection-induced immunity wanes with time, but health officials believe it still explains the low rate of COVID-19 deaths and hospitalizations compared to earlier points in the pandemic.

A stable supply of treatments such as Paxlovid has helped reduce severe outcomes, although the latest research about the antiviral drug was mixed. Researchers reported in Wednesday's New England Journal of Medicine that Paxlovid protected seniors against COVID-19 deaths and hospitalizations in early 2022 but not younger adults.