The rate of new deaths and confirmed cases of COVID-19 in Minnesota continues to slow, even as the number of new cases is growing in other states following the resumption of public life.

Fifteen confirmed fatalities from COVID-19 were added to the state's death tally on Sunday. The 7-day average number of deaths in Minnesota has declined or remained flat each day since June 2, when it plateaued at 25.

Meanwhile, Minnesota added just 311 new cases of COVID-19 to its statewide tally on Sunday, bringing the total for lab-confirmed cases of the viral respiratory illness above 30,400. Although reporting delays mean that data in the current week may be incomplete, a review of past data shows the 7-day average increase hit a high-water mark of 729 on May 24 and has been declining since then.

Nationally, the United States has recorded more than 115,000 deaths among more than 2 million confirmed cases. The number of new cases is rising in states including California, Texas, Florida and Georgia, though some of the increase is due to increased testing. Case counts are declining in New York, New Jersey, Illinois, and Massachusetts, according to the New York Times' closely watched case tracker.

Minnesota's trend of declining COVID-19 case counts is happening as the overall number of test results for Minnesotans processed by public and private laboratories rises.

On Sunday, 9,718 new results were added to the more than 400,000 COVID-19 diagnostic tests performed on Minnesotans since the start of the outbreak.

The number of tests reported by the Minnesota Department of Health varies from day-to-day, but Sunday marked the sixth consecutive day in which the 7-day average for new test results came in above 10,000, after never previously reaching that number.

That increase in processed test results coincides with calls by public-health officials for anyone who is taking part in demonstrations over the death of George Floyd to be tested for the illness — guidance that many observers expected to lead to increased transmission of COVID-19, given the massive civil-rights demonstrations in Minneapolis and St. Paul since Floyd's death on Memorial Day.

COVID-19 is caused by a novel coronavirus first reported last December. The virus has not been known to science long enough for researchers to reach definitive answers on why some people end up on mechanical breathing machines with severe pneumonia from it, while others just lose their sense of smell.

Symptoms generally take about 5 days to develop, but they can appear anytime between 2 and 14 days after transmission. Diagnostic testing that detects genetic traces of the virus in a nasal or throat sample — called "PCR" testing — is thought to be most accurate about three days after onset of symptoms.

Most people — 80% is the figure generally offered — experience mild to no symptoms after contracting the virus, formally known as SARS-CoV-2. Meanwhile, as many as 5% of cases may trigger a need for critical care in the hospital, including intensive care and mechanical breathing support.

People of advanced age, those living in group homes, and individuals with underlying health conditions are at greater risk of health, the statistics show.

All told, 96% of the 1,298 people in the state who have died from COVID-19 are 50 years old or older, a Star Tribune analysis shows. And 79% of them lived in long-term care or assisted living, including 11 of the 15 people whose deaths were reported Sunday.

The Centers for Disease Control and Prevention lists seven conditions that put people at greater risk for getting a severe case of COVID-19: Chronic lung disease, uncontrolled severe asthma, serious heart conditions, immunocompromise, obesity with BMI greater than 40, diabetes, chronic kidney disease requiring dialysis, and liver disease.

The virus can be transmitted by people who are not showing symptoms, including those whose symptoms haven't started yet. The World Health Organization said last week it's not clear how many cases of COVID-19 spread from asymptomatic individuals, after saying a day before that it was "very rare," according to biomedical publication STAT.

In Minnesota, about 26,100 of the total 30,400 confirmed cases of COVID-19 have passed a 14-day window for symptoms, and no longer need to remain in self-isolation. It's not clear how many of the 3,100 health care workers with positive tests for COVID-19 have been released.

As of Saturday afternoon, there were 186 people getting intensive care in the hospital for COVID-19, and another 183 people in regular hospital beds, according to the data released Sunday morning. Both counts plateaued in late May, though regular hospitalizations appear to have fallen off faster than ICU hospitalizations.