Antibody Testing
Posted on 04/27/2020

The news and social media are increasing coverage on serology, or antibody testing. The recent emergence of tests for detection of antibodies to SARS-CoV2—the virus that causes COVID-19—has been met with high hopes among health care providers, patients, and the media.

An antibody is something that is used by our immune systems to kill bacteria or viruses. Our bodies make antibodies when we have had a disease or when we are given a vaccine. Measuring whether a person has antibodies for a specific disease can be used to determine if that person may be immune to that disease.

Antibody tests are currently being developed for COVID-19 and can be a great surveillance tool, but they do have limitations. An antibody test cannot be used to diagnose someone who is currently ill with COVID. Because of the cross reactivity with ordinary Coronavirus, it is difficult to tell if a positive test is due to COVID or six other strains. These tests indicate presence or absence of antibodies but not whether the antibodies are protective. Having a positive test does not mean that you are protected from getting COVID again. More time and research are needed to understand how to use antibody testing results.

It is still unclear how much immunity a person gets after having the virus and how long it lasts.

Although some products have had limited review for emergency use authorization from Food and Drug Administration, most have had no review whatsoever. Furthermore, few of these tests have been independently assessed for accuracy.

Given this, the Health District is not recommending systematic serology testing at this time. Nor does the Health District routinely conduct any specimen collection or laboratory analysis for any of the COVID-19 tests. On April 27, BFHD sent a Health Alert to health care providers encouraging them to be aware of, and educate patients about, both the promises and the limitations of serologic testing.

The Health District will continue to monitor this emerging science with hope and caution.

 Adapted from Snohomish Health District and Thurston County Public Health