MINNEAPOLIS — Minnesota's COVID-19 positivity rate over the past seven days reached 15.6% on Friday, in an indication of the rapid spread of the omicron variant across the state.

State health officials have said they expect a new surge of case growth for at least the next month. The Star Tribune reported that Minnesota's previous positivity rate record came early in the pandemic in April 2020, when testing capacity was much more limited.

Health Commissioner Jan Malcolm said during a media briefing Friday that the increased use of at-home antigen tests — which aren't reported to the Health Department — has made daily case numbers less relevant in determining the full picture of case growth. The volume of daily cases coming into the Health Department has also been difficult for staff to keep up on, she said.

"Minnesotans need to know that the omicron surge most definitely has reached Minnesota and frankly circulating like wildfire all around the country simultaneously and in our communities around Minnesota," Malcolm told reporters.

More than 7,800 new infections were reported Friday, and nearly 1,200 Minnesota residents were hospitalized with COVID-19, including 269 in intensive care as of Thursday. The omicron variant — which spreads more easily than other coronavirus strains — now makes up around 90% of all COVID-19 cases statewide. Omicron also more easily infects those who have been vaccinated or had previously been infected by prior versions of the virus.

To meet the demand in testing, Democratic Gov. Tim Walz on Friday announced the expansion of two existing community testing sites in Inver Grove Heights and Stillwater. The announcement comes after a new site at the National Guard Armory in Anoka opened on Friday and testing capacity at a downtown St. Paul site was increased by 50%.

Early studies show omicron is less likely to cause severe illness than the previous delta variant, and vaccination and a booster still offer strong protection from serious illness, hospitalization and death.

But Malcolm said milder symptoms may cause people to be more cavalier about mitigation efforts. That could result in more cases overall and a higher likelihood of exposure for vulnerable communities, which would further strain hospitals.

The Minnesota Hospital Association in a statement urged people to look for tests in settings other than hospital emergency rooms due to a high number of patients statewide. Emergency departments, intensive care and surgical units are full, which is increasing wait times for medical emergencies and causing surgeries to be canceled.

"We have run out of words to describe what we are undergoing — a crisis does not even come close; hospitals are literally full," the association said. "We urgently need the public's help to keep our emergency departments available for medical emergencies. Please do not go to emergency departments or urgent care centers for a COVID-19 test."