As the United States broke another record for highest number of confirmed cases of COVID-19 in a single day, Minnesota case counts may also be rising.

Minnesota added 500 new lab-confirmed cases of COVID-19 to its statewide tally on Thursday, making it only the third report in a month's time to reach the 500s.

The seven-day average of new cases per day shows a decline that began in mid-May stopped a month later. The average number of new cases per day began trending upward again in mid-June and continued growing until the past few days. The most recent data are incomplete, because of reporting delays in the system.

Nationally, the U.S. added 49,932 lab-confirmed cases of COVID-19 on Wednesday to its total of more than 2.7 million. That one-day increase was higher than any prior daily total, including the day before, which itself was a record.

Minnesota has not seen the steep recent rises like in Arizona, Texas and Florida. But this week the New York Times' national coronavirus tracker moved Minnesota from the group of states with stable counts to the states seeing increases.

The state has had 37,210 confirmed cases of the viral respiratory illness since the first case was diagnosed here on March 5. The state is conducting more tests for COVID-19 than ever before — 13,049 test results were reported Thursday — and state officials say about 3.7% of those tests are coming back positive for the novel coronavirus that causes COVID-19.

Meanwhile, 13 new deaths in Minnesota were attributed to the illness on Thursday, bringing the state's number of confirmed fatalities to 1,458, including 1,143 people who lived in long-term care or assisted-living facilities.

Thirteen deaths represent the state's largest single-day total since June 19.

However, deaths are tallied by the day that they were publicly reported, and some cases take much longer to classify than others. The seven-day rolling average shows death counts hit a high-water mark of 25 on June 2 and have been steadily falling since then to the current average of seven per day, which has held steady for a week.

Of the deaths reported Thursday, eight happened to people who lived in group-living settings. The youngest person to die was in their 50s. Hennepin County recorded four deaths of people in their 80s.

The number of people hospitalized for COVID-19 remained stable Thursday, with 123 people getting care in hospital intensive-care units and another 151 in normal hospital beds.

Most people who get the illness don't need hospitalization — about 80% of cases are classified as mild because the person doesn't need care in a hospital. But as many as 5% of COVID patients may require critical care, including some who will need intensive care like having a breathing tube inserted for a ventilator.

People can spread the virus regardless of whether they have symptoms. On average, symptoms like fever, chills and coughing begin about five days after transmission, but they can appear between two and 14 days after the virus is acquired. Laboratory-based testing to diagnose COVID-19 peaks in accuracy about eight days after the virus is acquired.

Though scientists don't yet understand why the virus hits some people much more severely than others, statistics show several factors that increase a person's risk, including advanced age and living in a group home.

The Centers for Disease Control and Prevention says a range of chronic health conditions can also contribute to greater risk, regardless of age.

The CDC's list has evolved over time. As of June 25, the CDC says several conditions definitely drive increased risk, including chronic kidney disease, COPD, immunocompromised from organ transplant, obesity with BMI over 30, serious heart conditions including heart failure, sickle cell disease and Type 2 diabetes.

In addition, the CDC now says a host of other conditions may contribute to greater risk: Type 1 diabetes, moderate to severe asthma, tobacco addiction, vascular disease affecting blood supply to the brain, hypertension, neurological conditions like dementia, liver disease, pregnancy, scarring in the lungs, and immunocompromised from bone marrow transplant, HIV or medications.

Joe Carlson • 612-673-4779