Minnesota reported another 779 novel coronavirus infections on Friday across 64 counties, where local leaders and residents are now eyeing case growth as a determining factor in if or how their schools will open this fall.

The Minnesota Department of Health on Friday also reported six deaths from COVID-19, the infectious disease caused by the virus. State totals since the start of the pandemic are now 1,600 deaths and 54,463 lab-confirmed infections.

Growth in lab-confirmed infections as usual was largest in Hennepin County, where the addition of 227 such cases brought the county total to 17,316.

Hennepin is teetering at an infection rate of above 20 per 10,000 people per two weeks — a key threshold in Gov. Tim Walz's new school reopening plan for whether students will have classes in the fall that are live, remote or a combination of the two.

Another single infection was reported Friday in southwestern Pipestone County, which has the state's highest rate in the last two weeks of 70 cases per 10,000 residents. Schools in that county would be encouraged to conduct all classes online at that rate — though that rate could change dramatically in the next month.

Health officials for weeks have urged Minnesotans to wear masks, practice social distancing and cover coughs in public to reduce the spread of the virus that is particularly harmful for the elderly and people with underlying health conditions.

More than 80% of COVID-19 deaths have involved people 70 and older, even though they make up only 9% of the lab-confirmed infections. Five of the deaths reported Friday involved people 70 or older, but one involved someone from Olmsted County in the 20s age range.

Now, state officials said Minnesotans have the added incentive of using these strategies to reduce case growth that in turn could lead to more in-school classes for students. The state threshold is fewer than 10 cases per 10,000 people per two weeks for schools to consider all in-person classes.

"This plan alone won't work if community spread accelerates," Walz said.

Health officials remain concerned that recent increases in lab-confirmed infections could result in more deaths and hospitalizations — as has happened in Southern and Western states. The state on Friday reported that 312 Minnesotans with COVID-19 were admitted to hospitals, and that 151 of them needed intensive care due to breathing problems or other complications. That is the highest ICU number reported since June 27.

Case growth has increased in part due to more diagnostic testing. The state reported 16,660 more test results on Friday. However, the positivity rate of tests has increased to nearly 5%, which suggests the virus is spreading more broadly as well.

Case growth also started increasing after the June 10 limited reopening of indoor bars and restaurants, which have been the sources for numerous outbreaks among young adults. Lab-confirmed infections have increased 116% overall since June 1, but 155% among children 0-5, 257% among youth aged 6 to 19, and 177% among young adults in their twenties.

Recent research out of South Korea and other nations influenced the new school reopening strategy, said state Health Commissioner Jan Malcolm. The results showed that teens can spread the virus widely like adults, but that younger children are mostly getting infected by adults and are not significant spreaders of the virus themselves.

The new school reopening guidance would consequently encourage in-person classes for elementary schoolchildren in counties with moderate levels of COVID-19 activity, but not for high school students.

"When we talk about kids not being at risk for severe disease themselves or not being transmitters of the virus, we need to be more specific about the fact that that differs in some important ways by age group," Malcolm said.

Walz said the variations in transmission by age explain why he pursued a county-by-county response strategy for school reopenings amid the pandemic, but a statewide strategy for the shutdown last spring and the gradual reopening of businesses this summer.

"As we learn more and we get better at controlling the transmission and we get better at identifying who spreads it faster ... that can influence how we can go about making some of these decisions," Walz said.

Jeremy Olson • 612-673-7744