Minnesota reported 435 new confirmed cases of COVID-19 on Sunday and 24 deaths, but also a sharp rise in the number of people who have recovered and no longer need to be isolated.

The number in isolation declined by 618 people, including the 24 who died. Even after removing those, Sunday saw the largest single-day increase in the people released from self-isolation since the earliest days of the pandemic in Minnesota.

Meanwhile, the number of new cases reported Sunday was in line the recent trend of several hundred new cases of the illness a day. State officials have set aggressive goals for ramping up coronavirus testing in the state, while warning the public to expect increasing numbers of confirmed cases as surveillance efforts expand.

Hospitals and state public-health officials have been reporting the results of more than 3,000 tests per day since Thursday. The numbers the Minnesota Department of Health reported Sunday included 3,323 tests in the 24-hour period that ended at 4 p.m. Saturday.

Nearly 83,000 tests have been completed in Minnesota to detect the virus that causes COVID-19. All but 13,000 of them were done by private hospitals and laboratories, though all positive test results are reported to the state.

COVID-19 is caused by a novel coronavirus called SARS-CoV-2, which surfaced last year in China and spread into a global pandemic that state officials have called an act of nature. Dramatic public health efforts to limit the spread have led to widespread closures of schools, workplaces and public areas, and caused more than 30 million Americans to seek federal jobless benefits in the past six weeks.

All told, Minnesota has had 6,663 cases of COVID-19 confirmed with testing since the first case was diagnosed just over eight weeks ago in the state. Of those, 3,015 cases, or 45%, have returned to health and no longer need to remain isolated. That figure includes people whose improving health has removed the need to self-quarantine, as well as people who don't need care because they have died.

Minnesota surpassed 400 deaths on Sunday, as the new deaths brought the death toll to 419. Nationally, the U.S. has recorded more than 64,000 deaths, including 1,829 reported Sunday.

"We express our condolences to the families and friends of those who died," Minnesota Health Commissioner Jan Malcolm said in a statement Sunday.

Most people who get COVID-19 don't suffer devastating illness, but a small proportion have organ failure or severe respiratory compromise and end up in intensive care. Advanced age and underlying health conditions increase the health risks.

The epidemiology is still evolving, but the best reports available today say about 80% of COVID-19 cases involve mild to no symptoms, and don't require hospitalization. The percentage who need critical care in a hospital is generally thought to be about 5%, though the severity estimate may decline as widespread testing reveals previously unknown cases.

The statistics published Sunday by the Minnesota Department of Health showed 373 people in the hospital for COVID-19, including 155 in intensive care.

Public health officials in Minnesota have published a disease-progression model that assumes 27% of people aged 80 or more will need to be hospitalized if they get COVID-19, and 70% of them would eventually be moved to intensive-care unit (ICU) beds in the hospital. The ICU is where invasive critical-care devices like mechanical ventilators are used, though not all ICU patients go on a ventilator.

Meanwhile, Minnesota's epidemiological model assumed fewer than 5% of people aged 49 or less would need hospitalization, and only 6% of them will need to be moved to the ICU once hospitalized.

Besides age and underlying health conditions, residing a in group-living facility can be a risk factor. Just over 80 % of the fatalities in Minnesota have been residents of long-term care or assisted living facilities. Twenty-one of the 24 deaths reported Sunday occurred in long term care facilities.

In Winona County, residents of the Sauer Health Care facility for skilled nursing and hospice services accounted for at least 14 of the county's 15 deaths from COVID-19, Malcolm confirmed last week. That means about 20% of the 67 confirmed cases in the southeastern Minnesota county resulted in the deaths of people at the same facility.

Over in Nobles County, in the southwestern part of the state, a fast-moving outbreak among working-age employees at the JBS USA pork-processing plant in Worthington led to mass testing that documented 940 cases as of Sunday's tally. Yet the county has recorded a single death from COVID-19.

In both counties, as in the rest of the state, health officials caution that a lack of widespread and reliable testing for COVID-19 means there's no sure way to know how many cases truly exist in a given community, or what the actual death rate is.

Because no test for COVID-19 is perfect and the virus can be spread by asymptomatic people, Gov. Tim Walz has urged Minnesotans to wear protective masks in public to catch breath droplets that spread the virus.

"We continue our work along with many partners around the state to protect Minnesotans and prevent additional deaths," Malcolm said Sunday. "It is very important for all Minnesotans to do their part in that effort by following social distancing guidelines and other public health recommendations."

The state recommends people avoid gathering with others outside their homes and maintain 6 feet of space between themselves and others when they do have to leave. Residents should wash their hands often, cover coughs and sneezes, and regularly clean surfaces and objects that are touched often.

Last Thursday Walz extended a statewide stay-at-home order until May 18 that generally requires Minnesotans to remain at home and to work from home if possible.

The order strongly encourages, but does not mandate, that all residents wear manufactured or homemade face coverings in public places where it is hard to stay 6 feet apart at all times, like the grocery store and other essential businesses.