Live Mic: Doctor explains antibody testing for COVID-19

SALT LAKE CITY — There are many conversations surrounding the topic of antibody testing for COVID-19.

But, what exactly is antibody testing?

Your body makes antibodies when in fights infections like COVID-19. So, a blood test could identify if you’ve ever been infected with coronavirus and also tell health care workers how widespread the infection is.

Dr. Patricia Slev, the immunology section chief at ARUP and associate professor of pathology at the University of Utah, joined Lee Lonsberry on Live Mic to explain the next step in antibody testing.

“We’re all familiar with the swab test where you get a Q-tip inserted up your nose, and let’s you know if you have COVID-19, but this antibody testing is a whole different ball of wax. Could you explain that for us, please?” Lee asked.

“Antibody testing involves the traditional blood draw,” Slev said. “Swab tests or molecular tests involve viral genetic material and determine whether you’re currently infected with the virus.

“Antibody test detects antibodies, which are proteins that develop in an individual as they are trying to fight the disease,” Slev explained.

Developing a COVID-19 test

Slev said the antibody test ARUP is now developing for IgG antibodies, which are more likely to show up later after you’ve recovered from coronavirus.

An IgG or Immunoglobulin G is the most common antibody. IgG is in the blood and other body fluids and protects against bacterial and viral infections.

“If the IgG antibody is detected in an individual, it suggests that individual has been exposed to COVID-19 infection,” she said.

“And who no longer has that or has immunity to it? What does a positive detection of this test tell us about that individual?” Lee asked.

“To date, we do not know if the presence of antibody equals immunity. So I want to make that very clear. We do not have definitive proof to date that the presence of the antibody equals immunity,” Slev noted.

“We also don’t know the duration of the immunity. So if we detect IgG, we don’t know how long it will be present. So individuals who have symptoms and who you have to diagnose for COVID-19 infection, molecular testing is the recommended test,” Slev said.

Immunity

“How do you determine if somebody has built up an immunity to any virus?” Lee asked.

“As we become familiar with a virus and its infection patterns, disease course and the type of responses that an individual develops…then we can follow these antibody kinetics to see how long these antibodies are present.

“If a person is positive for these antibodies, does it prevent reinfection or provide protective immunity? But that takes time, and so those studies are ongoing for COVID-19,” Slev said.

“Is it more common than not for an individual to have a positive antibody test and then be immune from that virus?” Lee questioned.

“It is possible and that is a common finding, but again each infectious disease or each pathogen or virus is different,” she said. “So just because it’s true for one infection, doesn’t mean it’s true for another infection.”

“Of what use is this information?” Lee asked.

“One application of this information, for example, is to perform this testing on health-care workers who have been on the front lines to see if they have been exposed to the virus,” Slev said.

“Another application could be surveillance…because right now we do not know the true rate of infection. Some individuals, for example, are asymptomatic,” Slev said.

“So using the test …to determine the true rate of infection in the community, regional or national levels is one application of the test that will give us very important information, particularly since we suspect some individuals may be asymptomatic.”

Live Mic with Lee Lonsberry can be heard weekdays from 12:30 p.m. to 3:00 p.m. on KSL NewsRadio. Users can find the show on the KSL NewsRadio website and app