Antibody testing - what is it?

We’ve received a number of inquiries from the community about antibody testing for COVID-19. Antibody tests, which are also called serological tests, look for COVID-19 antibodies in the blood of patients who have either recovered from the illness or who were asymptomatic.  Typically, antibody tests help public health officials determine the true rate of infection among a population. 

Sonia Jordan, Director of Informatics for Lawrence-Douglas County Public Health, said that early scientific research is showing that an antibody test is not considered reliable until around 15 days after the onset of symptoms.  This means that an antibody test—when we have one that is reliable—will only be valuable later on the illness and will not be valuable in the early stages of determining if someone truly has COVID-19 or not.  

“Antibody (or serological) testing creates the possibility of exploring disease prevalence within a population and may even provide a roadmap for re-opening the country as we move from disease mitigation efforts to a return to normalcy,” said Dr. Christopher Brychel, infectious disease specialist at LMH Health. “Serology is unlikely to have a role in acute disease diagnosis, but may provide an additional tool to defeat an invisible enemy. In order for a test to provide meaningful information, we have to ensure that it has both the ability to detect disease (reliable sensitivity) and that a positive test truly indicates disease detection (high specificity). At this time, available assays do not appear to reach that benchmark but we are hopeful that will change in the near future.” 

Brychel added that knowing the significance of specific antibody levels in the context of immunity is paramount to successful intervention. “That data is still in its infancy,” said Brychel. “I am hopeful that in the near future, not only will we have a reliable test, but also the knowledge of how to apply this test to our patients in a meaningful fashion that is congruent with CDC and local public health guidelines.”