COVID-19 hospitalizations increased last summer after states ended stay-at-home orders and reopened businesses, according to a study by Minnesota and Indiana researchers that is among the first to chronicle the impact of policy decisions in response to the pandemic.

While it was always assumed that reopenings would result in more corona­virus transmissions — and consequently more hospitalizations and COVID-19 deaths — the study provided proof that will inform future public health crisis decisions, said Pinar Karaca-Mandic, a professor in the University of Minnesota Carlson School of Management who co-authored the study in the journal JAMA Health Forum.

"The really important thing from a policymaking standpoint is, what is the trade-off? One needs to know the trade-off" when weighing restrictions vs. open businesses and schools, she said.

Examining pandemic levels from mid-April through July last year, the researchers found that hospitalization rates stabilized before states lifted restrictions, and then increased weeks later after people resumed activities and increased opportunities for viral transmission. Nationally, 5,319 additional people were hospitalized for COVID-19 per day following state reopenings last summer, the study found.

The hospitalization paper was one of two published Friday with Minnesota co-authors that assessed the fallout of a coronavirus pandemic that has caused 604,971 known infections in the state and 7,572 COVID-19 deaths. The totals include 111 new infections and 11 deaths reported Friday.

More than half of U.S. public health workers surveyed in March and April reported at least one mental health symptom such as anxiety or depression, according to a paper published by the U.S. Centers for Disease Control and Prevention. Minnesota's state epidemiologist, Dr. Ruth Lynfield, co-authored the paper, which included survey responses from numerous public health workers in the state.

The common denominator of both studies is that they substantiated fallout that had long been presumed about the pandemic and the frenetic efforts by governments and health care providers to respond to it.

"It's going to take us a while, I think, to really understand the impact of this pandemic in so many different areas," Lynfield said.

Public health workers encountered resistance or even hostility when they investigated complaints of a bar that wasn't enforcing social distancing, or asking an infected person about any close contacts who may have been exposed to the virus. But they also had to do these jobs while facing the threat of COVID-19 themselves and in their families.

The surveys were conducted during a third pandemic wave this spring. Prevalence of mental health issues might increase as the workload declines, said Susan Palchick, director of Hennepin County Public Health. "People were still on an adrenaline high. Now, as things quiet down a bit, is when some of those things are really hitting people."

State health officials have credited the vaccination of more than 3 million people 12 and older in Minnesota for shortening the spring wave.

The state remains on track to fall just short of its goal of providing vaccine to 70% of people 16 and older by July 1 — with a current rate of 66.6%.

The payoff shows in the COVID-19 hospitalizations in Minnesota that declined from a spring peak of 699 on April 14 to 107 Thursday.

Minnesota was the 24th state to initiate restrictions in late March last year, according to the hospital study, specifically with Gov. Tim Walz issuing a stay-at-home order and a closure of nonessential businesses along with schools.

The study assessed changes in hospitalizations in Minnesota starting in late April 2020, when some retail and takeout business resumed, even though the state maintained its stay-at-home order until May 18 and kept bars and restaurants closed until June.

The U's COVID-19 Hospitalization Tracking Project contributed data for the study, which found an association between the end of state stay-at-home orders and the rise in hospitalizations, but didn't necessarily prove that one caused the other.

State-specific results weren't part of the study, but Karaca-Mandic said it did find that states that gradually phased out stay-at-home orders ended up with higher hospitalization rates than those that ended restrictions all at once. The phaseouts probably were implemented by states with more severe pandemic waves. That likely explains why they continued to have more hospitalizations despite a gradual reduction in restrictions, Karaca-Mandic said.

Jeremy Olson • 612-673-7744