Minnesota’s public health lab is restricting criteria for COVID-19 testing following a surge of activity that taxed its supply of kits and chemical reagents needed to confirm the presence of the corona­virus that causes the illness.

Testing by the state’s public health lab is now being reserved largely for hospitalized patients, health care workers and residents of long-term care facilities, the Minnesota Department of Health announced Tuesday.

“We need to be focusing on testing those individuals for whom the positive results will make a significant difference either in their care or for our health care system,” said Kris Ehresmann, state infectious disease director.

The state as of Tuesday had conducted more than 2,300 tests and identified 60 cases of COVID-19, the respiratory illness caused by the coronavirus that first emerged in Wuhan, China, in December. Three cases so far have involved people whose infections couldn’t be traced back to recent travel or to other sick people, meaning that the virus is now spreading from person to person in Minnesota.

The state has responded with unprecedented restrictions to limit exposure to the virus, including the closure of dine-in restaurants, bars, theaters, fitness clubs and other gathering spaces, and the shutdown of K-12 schools that will start Wednesday and last at least until March 27.

Ehresmann said the reduced testing only increases the urgency for Minnesotans to comply with these mitigation steps and to stay home when sick. People with respiratory illnesses are asked to remain isolated for seven days after symptoms first appear or fever-free for three days, whichever is longer.

“Certainly the governor has made decisions and enacted things that limit people’s opportunity for exposure,” Ehresmann said, “but ultimately it’s Minnesotans themselves that need to comply.”

State and federal agencies faced public and political pressure to increase testing as well as criticism for initially restricting testing to people with symptoms who had traveled to China or other countries where the virus emerged. Testing in Minnesota surged after the state followed federal guidance two weeks ago and gave physicians discretion to request tests.

State officials were budgeting initially for testing capacity of as many as 100 patients per day or 300 per week, but their lab tested samples from 443 patients in a 24-hour period between Monday and Tuesday, according to the latest Health Department figures.

Asked whether opening up the testing criteria was a bad decision in retrospect, Ehresmann said, “there have been a number of decisions that have been made that we don’t have control over.”

Inconsistent messaging from the White House and President Donald Trump was part of the problem, as doctors followed his statement that “anybody that wants a test can get a test,” said Dr. Rahul Koranne, president and chief executive of the Minnesota Hospital Association.

“The health system responded appropriately and started testing more people and then we find out there is actually a shortage,” he said.

Gov. Tim Walz sent a letter to Vice President Mike Pence last week, seeking an increase in COVID-19 tests. The state hoped to increase its capacity to as many as 15,000 tests per month.

Part of the problem is a global shortage of a chemical reagent that is used to extract nucleic acid from saliva or nasal samples to determine if the coronavirus is present.

However, alternative tests may soon be widely available due to a decision Monday by the U.S. Food and Drug Administration to allow new point-of-care and laboratory diagnostic tests for COVID-19 to go onto the U.S. market. The guidelines say test-makers need to independently ensure that the tests work and include disclaimers noting the test is not definitive and has not been reviewed by the FDA.

A Salt Lake City manufacturer is preparing to distribute its versions shortly, while St. Paul-based Ativa Medical said the FDA’s announcement may speed up manufacturing and eventual distribution of its point-of-care device and coronavirus test.

Mayo Clinic launched its own testing last week, but officials with the Rochester, Minn., health system did not reply Tuesday to e-mails about whether the global supply shortages would affect its criteria.

Testing by Minnesota’s public health lab is being reserved now for hospitalized patients, because positive results could make them eligible for antiviral drug studies that are underway in the race against this pandemic, Ehresmann said. Negative tests would allow hospitals to move patients out of rooms, such as those with negative air pressure, that are needed for COVID-19 cases, she added.

Test results of health care workers also could determine whether they must stop treating patients, and whether others in their clinics or hospitals may have been exposed.

Two patients told the Star Tribune they were screened via a visit to M Health Fairview’s OnCare telehealth portal and scheduled to go to a drive-through site to give a nasal or saliva sample. They received last-minute calls telling them not to show up, and M Health Fairview has since suspended its drive-through collection activities.

“I do not feel well … It could be due to something else but we really should be knowing what’s going on,” said a frustrated Lindsay Sandin, who was told not to go to the drive-through site in Brooklyn Park.

Health officials lamented the lack of testing. Koranne said more testing would provide early warnings to hospitals about when and where to expect surges of patients.

“The experience would have looked very different” with early, aggressive testing, he said, “but that is now behind us.”

Roughly 80% of COVID-19 cases result in mild symptoms, but people who are older and have other health problems appear particularly at risk for breathing problems and pneumonia that can result in the need for intensive care.

Ehresmann said she wants more testing as well, but the state can use its ongoing influenza surveillance as a proxy for whether the coronavirus is spreading. She added that the state will consider loosening restrictions if it receives more testing supplies and kits.

One positive, though, is that less testing means more people with mild symptoms will manage their illnesses at home and stay away from clinics and hospitals that can then focus on severe cases.

That, she said, could “ease some of the burden on our health care system.”

Staff writer Joe Carlson contributed to this report.

Correction: Previous versions of this article misstated the length of time health officials recommend self-isolation for people with respiratory illnesses. They are asked to remain isolated for seven days after symptoms first appear or fever-free for three days, whichever is longer.