A COVID -19 anti-body testing trial is underway in select counties in Utah with Summit County participating in the program. Medical experts warn people not to use the results as a license to discontinue proper distancing and sanitization practices.
Intermountain Healthcare Immunologist and Micro-biologist, Dr. Bert Lopansri says anti-body testing is commonly used to diagnose infections, particularly when there is no test available to identify the organism causing the infection. He says it’s an important clinical tool used for viruses such as Sars and other COVID viruses. He says the situation with COVID-19 is unique and new to the world.
“These are new tools so there's not been extensive information about how these tests work and how they perform. There have been numerous case series and case reports coming out of different parts of the world about the antibody response to this particular viral infection. We're learning every day but there are many uncertainties about antibody tests currently. So at Intermountain, as we roll these tests forward we are being very cautious until we get a better understanding about the significance of these antibody test results.”
Dr. Lopansri anticipates there will be many papers written as more data is collected.
They’re recommending using the tests on people who have been admitted to the hospital with severe respiratory tract infection. Testing would be done 10 days to 2 weeks after the patient develops symptoms because there is a better chance they would establish anti-bodies if they had been infected with the virus.
“Anti-body tests should not be used to diagnose acute infection but in some patients who have been admitted, they've had numerous COVID testing with molecular tests that have been negative and in that circumstance we’re waiting until enough time has elapsed for the body to develop antibodies and then we're recommending testing.”
Other groups they’re planning to test are patients and caregivers who had respiratory tract infection that was undiagnosed but have recovered. They’ll also use it for caregivers who have had high risk exposure to infected patients.
“And then the fourth one would be these large population- based studies which numerous groups are conducting at this time. The CDC has been conducting antibody tests. The University of Utah has several studies underway and we are collaborating with folks in different populations.”
They don’t have the data to know how COVID-19 immunity compares with a typical influenza infection.
“We’re learning about COVID right now and in the next several weeks we should get more information about how the antibody response develops to COVID or to SARS CO V2.”
Lopansri says the number of people infected will play a role in herd immunity. But there are public health concerns that come with a widescale spread of the disease.
“And the biggest concern is that it will make its way to the vulnerable population and it will lead to increased numbers of admission and it would eventually exceed the surge capacity in our hospitals.”
Lopansri says there is a correlation with how severe the disease symptoms were with the robustness of the antibody response. He says about 60% of people show an antibody response by day seven of having symptoms. By day 14, he says, over 95% show an antibody response.
“One of the major unknowns is how long does antibody response last? Do they wain in time or is this something that is a long-lasting response? The other major uncertainty is whether, or not the response denotes true immunity."
When people get a positive serology, anti-body test, it is not a ticket to go out and interact with the community at will. They plan to use the tests to assess the spread of the infection in the community. They also may use the test to assess patients who have symptoms but a negative nasal swab test. They want to look at high risk exposures to determine if someone has been infected asymptomatically.
They’re asking people to consult with their doctors about getting an antibody test. Lopansri suggests testing occur for people who suspect they’ve had the illness or have been exposed.
