Mayo Clinic's COVID-19 model predicts Minnesota's record wave of coronavirus infections will peak Jan. 26 and rapidly decline.
A quick peak to Minnesota's fifth pandemic wave would be welcome news, with the state on Tuesday reporting another 10,651 infections and 29 COVID-19 deaths. Tuesday's report, which updated pandemic activity in Minnesota through 4 a.m. Friday, included the deaths of three Minnesotans younger than 50 and increased the state's toll in the pandemic to 11,000.
The omicron variant is fueling the wave, and the Mayo model has learned from its spread elsewhere, said Curtis Storlie, its co-creator. The peak could come as early as Saturday or as late as Feb. 1.
"In Minnesota, all we're seeing are things going up and up and up, but around the country there are a lot of places where it's going down and down and down right now," he said. "We've seen it peak in several places now. That's giving the model more information."
State health leaders cautioned that hospitalizations and deaths, delayed consequences of infection, could continue to increase for a few weeks after the peak.
COVID-19 hospitalizations in Minnesota have increased this month from 1,329 on Jan. 2 to 1,610 Monday. However, the cases requiring intensive care have declined in that period from 283 to 248 — reflecting the lower rate of severe illness caused by omicron.
COVID-19, influenza and other medical concerns combined to fill 977 of 1,013 available adult intensive care beds in Minnesota on Monday — a 96% occupancy rate that is high, but not as bad as it was late last year when the number of open ICU beds was in the teens.
Minnesota's infection rate will remain at record levels leading up to any peak and remain high for days or weeks after that until enough people have immunity from vaccination or previous infection to slow viral spread. The state's positivity rate of diagnostic testing reached 22.2% in the seven-day period ending Jan. 7.
"The surge is — frankly it's scary how many cases we are seeing," said Dan Huff, assistant commissioner of the Minnesota Department of Health.
Minnesota's per-capita infection rate is at its highest in the pandemic despite the rising popularity of at-home rapid antigen COVID-19 tests that are not reported to the state. Minnesota's infection rate ranked only 38th highest in the nation last week, but it is rising even as rates are falling in Florida, New York and other states with early omicron exposure.
"That's the silver lining," said Matt Binnicker, Mayo's director of clinical virology. "It's a crazy roller coaster ride of a fast rise to the peak, then a quick drop-off from there."
Mayo's forecast is similar to a projection by the Institute for Health Metrics and Evaluation in Washington state that indicates Minnesota's peak already occurred Monday.
State leaders are hopeful that vaccination progress in Minnesota blunted the severity of the omicron wave. More than 4 million Minnesotans have received at least first doses of COVID-19 vaccine, or more than 77% of eligible residents 5 and older, according to the Centers for Disease Control and Prevention.
Of those who are fully vaccinated, more than half have received booster doses, which help to reduce risk of severe COVID-19, hospitalization and death. Minnesota ranks second among states for its booster rate.
Breakthrough infections in fully vaccinated Minnesotans remain a concern — with the state on Tuesday reporting they made up 46% of 18,039 infections recorded in the week ending Dec. 18. However, the proportion of COVID-19 deaths involving fully vaccinated people has declined from 51% in the last week of October to 27% in mid-December — potentially showing the protective effect of booster doses.
The proportion of COVID-19 hospitalizations involving fully vaccinated Minnesotans has declined from 35% to 25% in that same time period — when omicron was replacing delta as the dominant coronavirus strain.
Minneapolis-based Allina Health reported Monday that 254 of its 440 COVID-19 hospitalizations involved people who hadn't been vaccinated. Of the 52 patients on ventilators because of extreme lung damage, 44 were unvaccinated and eight were fully vaccinated but without boosters. The system reported 60 COVID-19 hospitalizations involving patients who were fully vaccinated with boosters, but none needed ventilators.
Minnesota enjoyed a brief stretch of low COVID-19 activity in June, but then the fading alpha variant was replaced by the faster-spreading delta. Immunity in early vaccine recipients began to wane six months after their initial shots, fueling a prolonged wave.
Storlie said the emergence of a new wave after omicron remains possible, and people should continue to seek boosters and follow public health guidance.
"We're going to have a honeymoon period," he said. "After that, we just don't know, right? Omicron came out of the blue. You can't really predict that."