Antibody testing for COVID-19 is available in Fairbanks, but what does it tell us?
The term “antibody testing” has been making the rounds across national and international news outlets.
“Antibodies are proteins made by your immune system to fight infections,” says Dr. Ashley Lundgren Strum, an internal medicine physician with Fairbanks Memorial Hospital. “And there are different types of antibodies: some are made when the infection first start, some can be used to show that an infection has cleared, and then some can be used to fight off or prevent the same infection from happening in the future.”
Strum’s last example perhaps best begins to set up the epidemiological usefulness of studying antibodies during a pandemic, since knowing how many people are immune to a specific pathogen can influence medical, social, political, and economic decision-making.
Currently, the hospital is offering antibody tests. However, these tests may not be immediately useful at the individual level.
“Each little virus or bacteria has things that are unique to it, and we call those antigens. And our body will identify those antigens and create antibodies specific to that virus or bacteria,” Strum says. “Now, there is some cross-reactivity, so an antibody that works, for example, for one coronavirus may work for other coronaviruses. Or a similar antibody may be produced to multiple coronaviruses.”
There is another reason why caution should be taken when considering antibody test results: because of the variable nature of any given antibody test’s ability to detect false positives versus true positives and false negatives versus true negatives, the tests become more accurate in communities with higher prevalence rates.
This, Dr. Strum says, makes them less useful in Alaska, and particularly less useful in Fairbanks and the surrounding borough, which has only seen patients test positive once again for the virus as of last week, after over one month without any new cases.
“We are not able to use [the antibody test] at this time to determine immunity,” Strum adds. “For example, not all antibodies produced by the body will prevent the same infection from occurring again.” She says that these are known as “neutralizing antibodies”.
Additionally, the tests do not reveal how
of the antibody is in a person’s system, or how
they will be there for.
Although it may seem like the usefulness of antibody tests is currently dubious, Dr. Strum is hopeful that the data from antibody tests being collected by the CDC from areas with higher prevalence will be more useful to the individual in the future. These will also be useful in learning about rates of asymptomatic disease, she says.
For residents who are interested in obtaining an antibody test, Dr. Strum recommends consulting with your physician.