UPDATE:First two cases in Michigan confirmed by Gov. Whitmer

COVID-19, the disease caused by the novel coronavirus, is spreading quickly in the U.S. By Tuesday morning, there were 808 confirmed cases and 28 deaths.

Yet 13 states, including Michigan, still don't have a single confirmed case of the virus, which causes, fever, cough and difficulty breathing with symptoms that can range from mild to severe.

So far, 63 people have been tested in Michigan for novel coronavirus, according to the Michigan Department of Health and Human Services. The results from 39 tests were negative for COVID-19, and 24 were still pending Tuesday evening.

State and local health officials have assessed and monitored 471 people for possible COVID-19 infections. Among them are people who were flagged at an airport screening by the U.S. Centers for Disease Control and Prevention, or people who had close contact with a person under investigation for COVID-19. Others may have been referred by their doctors to the local health department.

Some of the 471 people who were assessed and monitored have already completed self-quarantine. A total of 124 people remain under active monitoring, according to the MDHHS.

Of the 471 people who've been assessed and monitored for COVID-19 in Michigan, 408 have not been tested for novel coronavirus.

The state now has the capacity to test between 375 and 400 people, said Lynn Sutfin, a spokeswoman for the MDHHS.

That means that not everyone who wants a novel coronavirus test can get one. Because there are limited supplies of tests, health officials are using criteria set by the CDC to set priorities for testing.

"Health care providers, local health departments and MDHHS are working together to determine who should be tested for COVID-19," Sutfin said. "We have continually provided guidance to both health care providers and local health departments about who should be tested and specimen collection as we have received updates from CDC."

The latest CDC guidance was issued March 8 and suggests that doctors should use their judgement to decide whether a patient has symptoms compatible with COVID-19. Priorities for testing include:

Hospitalized patients with symptoms compatible with COVID-19 when testing would inform infection-control decisions

Symptomatic patients with chronic medical conditions or compromised immune systems that put them at higher risk for severe illness, such as diabetes, heart disease, people receiving immunosuppressive medications, chronic lung disease, or chronic kidney disease

Symptomatic adults ages 65 and older

Anyone, including health care workers, who, within 14 days of symptom onset, had close contact with a suspected or lab-confirmed COVID-19 patient

Anyone who has a history of travel from affected geographic areas — China, Iran, Italy, Japan or South Korea — within 14 days of their symptom onset

"There are epidemiologic factors that may also help guide decisions about COVID-19 testing," Sutfin said. "Documented COVID-19 infections in a jurisdiction and known community transmission may contribute to an epidemiologic risk assessment to inform testing decisions."

Some of Michigan's tests were purchased from a private vendor, Iowa-based Integrated DNA Technologies, Sutfin said. Those tests have been validated and approved for use by the CDC and the Food and Drug Administration.

Soon, she said, FDA-authorized testing will be available in clinical labs, too, which, she said, "will allow clinicians to consider COVID-19 testing for a wider group of symptomatic patients."

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Contact Kristen Jordan Shamus: 313-222-5997 or kshamus@freepress.com. Follow her on Twitter @kristenshamus.