Half of Minnesotans eligible for COVID-19 vaccine have received at least a first dose.

State health officials commended the progress but said more vaccinations are needed amid a third pandemic wave in order to bring Minnesota to a level of herd immunity that stifles the coronavirus that causes COVID-19.

"We really, truly are in a race against time to get Minnesotans protected," state Health Commissioner Jan Malcolm said.

The Minnesota Department of Health reported six more COVID-19 deaths on Friday and 2,299 infections, bringing the state totals to 6,995 deaths and 552,117 infections.

A sign of hope in this latest wave is that COVID-19 deaths haven't increased over the past month at the same rate as infections and hospitalizations — possibly because so many high-risk individuals have been vaccinated.

The state on Friday reported that nearly 2.2 million Minnesotans 16 and older had received COVID-19 vaccine — 50% of the eligible population — and more than 1.5 million had completed the one- or two-dose series. Nearly 85% of senior citizens have received vaccine — a key priority group that has suffered 89% of Minnesota's COVID-19 deaths.

New Mayo Clinic modeling research suggested that Minnesota would be in a much worse situation without vaccine because of reduced compliance with prevention measures and broader circulation of more infectious variants of the SARS-CoV-2 virus.

Had vaccine not existed, Minnesota might have seen a peak of more than 800 patients with COVID-19 needing hospital intensive care in this third pandemic wave — more than double the record 399 ICU patients on Dec. 1 during the second wave.

"It is difficult to untangle how much of this elevated rate of spread right now is due to new variants as opposed to changes in social behavior," the authors wrote in a study released online Thursday ahead of publication in the journal Mayo Clinic Proceedings. "Regardless of the reason, the absence of vaccinations in the current environment would have been likely to result in by far the largest surge to date."

The study was led by Mayo's Curtis Storlie and Dr. Sean Dowdy, who developed a model for forecasting COVID-19 impact on hospital usage. It also found that continued vaccination is necessary.

Had all vaccination activity ceased on April 6, the most likely scenario under the modeling is that Minnesota would have come close to 300 COVID-19 ICU admissions. If Minnesota had magically reached a 75% vaccination rate on that date, the modeling suggested that viral activity and hospital usage would quickly dissipate.

As it is, Minnesota hospitals on Thursday reported 671 COVID-19 cases taking up inpatient beds — including 165 who needed intensive care. That is lower than 699 hospitalizations reported on Wednesday.

The positivity rate of COVID-19 diagnostic testing in Minnesota increased to 7.4% — above the state caution threshold for viral activity. Growth in the positivity rate has leveled, but state health officials said that could be due to the lag in reporting of some test results rather than improving conditions.

State leaders urged continued mask-wearing and social distancing in public — as well as basic public health precautions such as covering coughs and staying home when sick — to reduce viral transmission.

"I'm afraid that the risk indicators still look like they are worsening, not leveling out," Malcolm said, "certainly not getting better yet."

The state on Thursday reported a total of 561 breakthrough infections in Minnesotans who have been fully vaccinated — including 66 hospitalizations and six COVID-19 deaths. Fully vaccinated means it has been 14 days since someone received a final shot.

State infectious disease director Kris Ehresmann said the COVID-19 vaccines are highly effective but don't prevent all infections or severe illnesses. The rate of known breakthrough cases is small — .005% of the roughly 1.1 million fully vaccinated Minnesotans — and many were asymptomatic infections identified through routine testing at nursing homes and other locations.

Jeremy Olson • 612-673-7744