Testing has revealed a steep rise in current COVID-19 infections in Montana. Now, many health care facilities are also offering a test that shows if a person was previously infected. Local medical professionals are advising caution to those considering antibody tests to confirm anything beyond curiosity.
Despite the growing number of medical facilities offering antibody tests in Montana, state pathologists and epidemiologists warn it’s still too early to draw anything conclusive from their data.
Tests are currently available at hospitals like Benefis Health System in Great Falls, St. Vincent Healthcare in Billings, Francis Mahon Deaconess in Glasgow, Bozeman Health Deaconess, along with blood donation centers like Vitalant and American Red Cross. Antibody tests aren’t covered by insurance plans but are included with blood donations.
Unlike the molecular or PCR tests that detect current infections with a nasal swab, antibody tests can reveal if a patient was previously infected with COVID-19 through a blood sample.
“The way the antibody works is, once somebody is exposed to any kind of virus, about two weeks, they won’t have any antibodies, they’ll have the PCR positive," Nero said.
That’s Dr. Christopher Nero, a pathologist and member of Bozeman Health Deaconess Hospital's COVID-19 Incident Command. Nero says since they began offering an improved antibody since June, they’ve been doing 50 to 100 tests a week.
“And after that initial infection, about a week or two later, the antibodies start to develop. So you could have potentially a false negative if you tested someone too early,” Nero said.
Antibody tests are typically used to detect either a false positive or false negative result from a previous test. For example, if a patient gets a negative PCR test but still shows all the signs for COVID-19, an antibody test could reveal this to be a false negative if they still developed antibodies.
Antibody tests could potentially show more cases in areas that lacked enough PCR tests early on. Although not enough antibody tests have been done in Montana to show this, Dr. Michael Brown from the Yellowstone Pathology Institute and St. Vincent Clinical Laboratory says an epidemiological study by the state health department or government could be done in the future.
“I think that would be appropriate. Then you’re testing a lot of people and you’re not making any medical decisions or any decisions on individual people from that result,” Brown said.
Dr. Brown explains the Food and Drug Administration (FDA) enacted an emergency use authorization for COVID-19 antibody tests due to the immediate need for testing in February and March. This led to a flood of different tests by companies without the same standards and regulations typically seen in FDA approved tests.
Unlike the PCR tests, the antibody tests were not as developed and results were unreliable early on. As more tests were used in labs and the FDA revised its guidelines, the tests have improved to detect proteins formed specifically from the coronavirus.
Dr. Nero with Bozeman Deaconess says antibodies will likely be used to also measure future vaccines’ effectiveness and patients’ immune responses to them.
“If someone gets vaccinated, when the vaccines come out, we’ll want to see: do they demonstrate an immune response? And you can measure the antibodies to do that,” Nero said.
Despite the antibody tests’ improved accuracy, local medical professionals like Dr. Wade Nelson with the American Society of Clinical Pathology and Benefis Health System warn their results may still give patients false impressions of immunity or protection.
“They think you’re protecting people by getting the COVID test, but you're really not. Testing isn’t going to fix anything because there’s no real treatment for it until there’s a vaccine,” Nelson said.
Dr. Nelson says that the soonest a vaccine could be developed, tested and regulated would be at least 12 months away and up to 18 months.
Another concern is the lifespan of the antibodies. A June study from China showed the lifespan of the antibodies developed from COVID-19 drop off after two to three months.
St. Vincent’s Dr. Brown says this means the tests are unreliable for revealing any long term immunization.
“Coming back and trying to do a test a few months afterwards to say, ‘Hey, did I have COVID?’ you’re at risk for getting a false-negative result because you’re no longer making those antibodies or at least they’re no longer detectable,” Brown said.
Dr. Brown and other health care professionals are currently only recommending the tests for people who recently showed symptoms of COVID-19 and were unable to get a PCR test or want to confirm a previous PCR test.
