ST. PAUL — In their first daily briefing on the state of coronavirus preparations in Minnesota, health officials said on Tuesday, March 3, that they currently have the kits in hand to test 800 patients for the virus and are no longer dependent on the CDC for diagnosis of probable cases.

Until this week, all testing had to be sent to CDC headquarters in Atlanta, which could only conduct 400 tests a day for the entire U.S. and faced a backlog.

"Now that we do have lab testing capacity, that will make a big difference in the timeliness of our ability to report results," said Kris Ehresmann, director of infectious disease epidemiology and control, at the Minnesota Department of Health. "We've really been constrained in lab testing both by the definition of those suitable for testing and testing capacity at CDC."

Where states had previously been told to observe what some say were too stringent requirements — to test only those with fever and respiratory symptoms requiring hospitalization who'd recently traveled to or had close contact with persons traveling to affected countries — Ehresmann said the state now "has great latitude to test individuals" with no traceable connection to foreign locales.

The state can now test those who have shown fever, cough and respiratory symptoms requiring hospitalization and who have received testing to rule out the flu and other respiratory illness. Ehresmann disputed a notion currently circulating on social media that shortness of breath is a symptom separating coronavirus from the flu.

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"There's not a sure-fire symptom" for identifying coronavirus, said Ehresmann. "We have so much overlap between COVID-19 symptoms and influenza that I don't think just having shortness of breath is enough to differentiate a need for testing. When we're talking to providers we ask that they should test for other respiratory illnesses, and if they don't see evidence of that, then calling us in is the thing to do."

Though the Health Department can now test up to 100 samples a day, to date it has only sent four samples for testing, all returning negative. Ehresmann said the state will not charge providers for the test, but that providers could assess charges. She added that the state expects tests from private labs to soon become available as well. "The FDA has opened the door for lab-developed tests, meaning that health systems such as Mayo Clinic would be able to develop their own laboratory tests."

Mayo Clinic confirmed on Tuesday it is in the process of developing its own coronavirus test.

"Mayo Clinic Laboratories is developing a real-time PCR test that can detect SARS-CoV-2 (i.e., the cause of COVID-19) in clinical samples," said Mayo spokesperson Ginger Plumbo in a statement. "We hope to have the test available in the next few weeks." PCR stands for polymerase chain reaction tests, genetic assays capable of determining exposure to the virus without antibodies having had time to form. Mayo said the test would be a saliva swab, and that the cost is not yet determined.

With up to 14 days of symptom-free transmission during its incubation period, and even then showing ambiguous symptoms that do not easily differentiate from a bronchial cold or flu, there have been few public health crises more in need of a fast, affordable, widely accessible diagnostic test than coronavirus. Compounding the urgency, the virus is more transmissable than the flu (albeit far less transmissible than measles), and, if early estimates are correct, potentially 20 times more lethal.

The CDC came under fire this week for recent delays within the U.S. compared to other nations in developing and distributing effective tests for the virus. An early effort to distribute tests manufactured by the CDC was halted after part of the test developed consistency problems. That problem has now been resolved, but critics say federal authorities could have utilized an effective test developed weeks ago within Germany, choosing instead to wait for their own test, effectively squandering valuable weeks for identifying asymptomatic carriers.

"It would have been great to have the test functioning a couple of weeks ago," said Ehresmann. "But by the same token the rapidity with which the CDC developed a laboratory test is remarkable."