Updated: 1:10 p.m.
A month ago, Gov. Tim Walz announced a $36 million strategy for coronavirus testing in Minnesota.
He described the plan, which harnesses the testing capacity of Mayo Clinic and the University of Minnesota, as a “moon shot” to bolster the state’s ability to detect and stop the spread of coronavirus.
“We are smothering this issue of testing, I’d argue, with talent better than any place on the planet,” Walz said in April.
The plan called for the state to ramp up its testing capacity to 20,000 coronavirus diagnostic tests daily. But it also called for 15,000 serology tests daily — blood tests meant to detect if someone has already been exposed to the virus.
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Those tests have been hailed as a key component to understanding how widely the virus has spread in the community, and therefore offer a key set of data that leaders can use as they consider paths to reopening. But while Minnesota appears to be steadily increasing its capacity for testing that diagnoses COVID-19, antibody testing hasn’t gotten off the ground.
What is a serology test?
A serology test — also known as an antibody test — relies on a blood sample to detect whether someone has developed antibodies to the coronavirus. The presence of antibodies is an indicator that someone has already been exposed to — and fought off — the virus, even if they never showed symptoms.
These tests differ from diagnostic tests, which rely on samples taken with a nasal swab to determine if someone has an active coronavirus infection.
Who can get a serology test — and how?
So far, the state hasn’t issued guidance on who should get this kind of test — and how they can get one. In Minnesota, the University of Minnesota and Mayo Clinic have each developed their own antibody tests, but they’re not yet widely being used.
Mayo Clinic, for instance, has conducted 70,000 tests to date — 13,000 of them in Minnesota — and does as many as 4,000 tests daily, said Elitza Theel, director of the infectious diseases serology lab at Mayo Clinic.
But because there’s no statewide effort to offer antibody testing for specific groups of people — as there has been for diagnostic testing — there’s no consistency so far in who is getting tested.
Theel said samples are arriving at her lab from in-state and out-of-state clients.
Some hospitals, including Mayo, are using the test to prescreen patients arriving for care. Some businesses are using them to screen employees. And individuals can ask for a test from their health care provider.
Antibody testing is a prominent part of the state’s three-part COVID-19 strategy: “Test, trace, track.” Why aren’t more people being encouraged to get the tests?
One reason state health officials say they have been reticent to suggest widespread testing is reliability. In addition to the Mayo and U of M tests, private companies have also developed their own antibody testing.
State officials say there are tests on the market that don’t produce reliable results. The Food and Drug Administration has raised the alarm about faulty tests on the market, and is more rigorously regulating them.
Theel says Mayo has a high level of confidence in its own test, which has earned emergency use authorization from the FDA.
But Dr. Ruth Lynfield, Minnesota’s state epidemiologist, said there are lingering questions about what to do with the results of even the most reliable tests. Scientists still don’t know if the presence of coronavirus antibodies detected suggest a person has some level of protection against getting the virus again. And if they do offer some protection, scientists don’t know how much — or how long it lasts.
“If you get a result and you are positive, that doesn’t necessarily mean that you are protected from getting infected again. That is the piece that we still need to learn,” Lynfield said.
And as the state inches toward reopening, Lynfield said getting a positive antibody test result may give someone a false sense of security — and might lead them to make decisions that could put themselves and others at risk of contracting the virus.
Are these tests useful at all?
Lynfield said that, while antibody tests aren’t generally useful on the patient level yet, that might change with more research.
“I’m hoping that some time soon, we will know more about protective immunity and use it more effectively,” she said.
But when it comes to the bigger picture, serology tests can help state health officials understand the virus’ prevalence in a given community. Lynfield said that the state will be involved in several studies in the coming months to better understand the coronavirus’ spread.
There are also two clinical uses that can be beneficial right now: In children and in helping patients still fighting the disease.
Lynfield said it’s appropriate to test children who present symptoms of an inflammatory syndrome that has recently been associated with the virus.
And Theel said identifying people who have coronavirus antibodies can help medical providers develop their convalescent plasma programs — which use plasma from people who’ve already been infected with coronavirus to treat those currently experiencing COVID-19.
Mayo Clinic is coordinating a nationwide program to collect blood plasma from people who have recovered from a coronavirus infection to help treat patients still fighting the virus.
If a person falls into one of those categories, how can they get tested?
At the moment, patients who think they should get antibody testing need to contact their doctor’s office for the referral. Because it’s a blood test, samples can be taken as they would for many other blood tests.
People who get positive results may consider participating in a nationwide study lead by Mayo Clinic that is looking at whether plasma from people who have had COVID-19 can be used to treat people who are currently fighting the virus. Mayo Clinic says they are looking for people to donate plasma within a month of a positive antibody test, as that's when the antibodies are strongest. Interested patients and physicians can learn more at uscovidplasma.org.