A surge in COVID-19 cases following the mass protests and riots over the May 25 police killing of George Floyd has not yet materialized, despite aggressive testing over the past two weeks of people involved in the demonstrations that roiled the Twin Cities.

The Minnesota Department of Health on Monday reported four more deaths and 308 more lab-confirmed cases of COVID-19, an infectious disease caused by a novel coronavirus. That is the lowest number of COVID-19 deaths reported in one day in the pandemic since April 13.

Only 1.5% of tests at four community sites last week of people involved in demonstrations turned up positive for the presence of the virus, suggesting that all of the shouting and crowding didn't result in widespread transmission.

"That is a relief," said Kris Ehresmann, state infectious disease director.

State officials warned that the positive trends could be upset, though, if Minnesotans stop complying with recommendations to wear masks in public and practice social distancing. Arizona and other states in the south were faster than Minnesota in scaling back restrictions on businesses and social mobility, and have seen cases spike upward.

Minnesota health officials are concerned that a declining trend in the median age of COVID-19 cases — now at 40.4 years of age — suggests that more young people are disregarding social distancing and spreading the virus.

Minnesota permitted limited indoor restaurant and bar service as of June 10, along with restricted reopenings of fitness clubs and entertainment venues. Ehresmann said the impact of those changes won't be known for another week or two.

Contact tracing interviews with people diagnosed with COVID-19 since June 3 found that at least 6.5% had been at restaurants before their infections — though it was unclear if they already had the virus or were infectious during these visits.

An increase in workplace infections is driving down the median age of those sickened as well. The state has been tracking outbreaks in food processing plants in southern Minnesota's Mower County — where there have now been 802 confirmed infections and two deaths.

"We all have to be doing our part to make sure that we are social distancing, wearing masks, all of those things," Ehresmann said. "We certainly don't want to see our cases increase and then have to dial back" on the reopening of business and activities.

The pandemic has caused 1,384 deaths and 33,227 known cases in Minnesota. The state also reported that 332 patients with COVID-19 were hospitalized on Monday, and that 156 required intensive care. The number of hospitalized patients increased by 10 since Sunday, but remains below the peak of 606 patients on May 28.

The latest figures come more than three weeks after some of the heaviest demonstrations over Floyd's death, and more than two weeks after a June 4 memorial event.

Many protesters did not wear masks, raising concerns that they would infect one another while shouting and standing in tight crowds. However, health officials hoped that the virus didn't spread as much outdoors.

Secondary impacts of the prolonged pandemic are beginning to show. The U.S. Centers for Disease Control and Prevention on Monday showed a decline since the start of the pandemic in emergency room visits for heart attacks, strokes and uncontrolled blood sugar.

Ehresmann said these trends reflect people who are no longer going to the ER — perhaps due to fear of COVID-19 exposure — and putting their health at risk.

Childhood immunizations also have declined as people have stayed away from clinics. The number of measles shots in the state in March was 70% below the same period a year earlier. While vaccination levels improved this spring, health officials worried that parents wouldn't seek them this summer because they usually time them with physicals for sports and activities and camps that may have been canceled.

"We could see a resurgence of vaccine-preventable — but still highly contagious — diseases at a time when our public health system is already strained in response to the pandemic," U.S. Sen. Amy Klobuchar, D-Minn., said in a letter sent Monday to the U.S. Secretary for Health and Human Services that called for more education on vaccinations.

Klobuchar on Monday also disclosed that her father — 92-year-old former Star Tribune columnist Jim Klobuchar — has COVID-19. The senators's husband had been hospitalized in March due to COVID-19 as well, but has recovered. Klobuchar said she spoke with her father outside the window to his room in an assisted-living facility and that he is doing OK.

Two of the four deaths reported Monday involved residents of long-term care and assisted-living facilities, bringing the statewide total to 1,095, or nearly eight out of 10 deaths to date. The majority of deaths have involved the elderly or people with underlying health conditions, including diabetes, asthma and diseases of the lungs, heart, kidneys and immune system.

Jeremy Olson • 612-673-7744