When state officials say they want to expand coronavirus testing in Wisconsin, they mean the diagnostic test that usually involves inserting a long cotton swab through the nose. The exam detects if you currently have the coronavirus.
But some health care organizations are also offering an antibody test. That involves taking a small blood sample to see if you previously had the virus and your immune system made protective proteins called antibodies to fight off the infection.
UW Health, which is part of the University of Wisconsin-Madison and mainly serves southcentral Wisconsin, began offering the antibody test last week at four clinics. Chief Quality Officer Dr. Jeff Pothof says the test may be right for people who are curious about COVID-19 but maybe couldn't get the nasal test.
"They want to know whether what they had was COVID-19 or not. If they're now recovered, and healthy, the antibody test might be right for them,” Pothof told WUWM.
Pothof says if large numbers of people take the antibody test, that may benefit society.
"It's understanding what percent of people in a community have already been exposed and have antibodies to COVID-19. Now, we don't know yet that those antibodies infer immunity against re-infection, but there are some studies going on and I think all of us are hopeful that it will, as least for a short period of time," Pothof said.
Wisconsin Department of Health Services Deputy Secretary Julie Willems Van Dijk says she agrees with the potential benefit of getting a broader look at who's had COVID-19. She describes the concept of disease surveillance.
"If we did sampling across our state and looked for antibodies, it would give us a good sense of what percentage of the population was exposed to and had COVID-19 because we know many people have no symptoms or very mild symptoms of the disease,” Willems Van Dijk said.
Pothof says he understands that others in the medical community are cautious about recommending the antibody test. For example, Dr. Ben Weston, director of Medical Services for the Milwaukee County Office of Emergency Management, says people thinking about taking the test should wait.
"On a national level, there are nearly 100 different antibody tests. Some are decent, some are terrible, and it's very hard to tell in-between. Right now, with an antibody test, if you have a positive result indicating you may be immune, that result is just as likely, if not more likely, to be a false positive due to the inaccuracy of these tests. So, there's a place for these tests in the future, but it's limited right now," Weston said.
Michael Osterholm, a professor of public health at the University of Minnesota, said last week during a national briefing that an antibody test needs a second, confirmatory test.
"Like we do with HIV, where we have an initial screening test. If you're positive on that, basically go to a confirmatory test so the entire answer is not just one, but it's a series of steps that allows you to know that,” Osterholm said during the national briefing offered by the USC Center for Health Journalism.
At UW Health, Pothof says he thinks his provider group is offering one of the better tests.
He says about 1,700 people have appointments to take it. UW Health is charging a fee, but Pothof says the federal government is requiring health insurance companies to pick up the bill without a patient co-pay. Pothof says UW lawyers are still figuring out if the uninsured also won't pay anything.
In the Milwaukee area, AdvocateAurora Health says antibody tests are available to patients who have an order from an AdvocateAurora physician. Froedtert and the Medical College of Wisconsin declined to comment on antibody testing for COVID-19 at this time.
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