COVID-19 Antibody Testing Update (March 2021)
Feb. 24, 2021
Director of Clinical Laboratories, Director of Molecular Pathology
Ordering antibody testing for SARS-CoV-2 based on vaccine status of the patient
Effective 2/10/21 orders can be placed for SARS-C0V-2 spike (S) protein antibody tests, EPIC LAB9165, SARS COV-2 IGG (VACCINE IMMUNITY). As the test name implies, this the best test to assess an immune response to vaccination with the three currently approved vaccines.
We still offer EPIC LAB8754, which has been re-named SARS COV-2 IGG PANEL 1 (DISEASE). This is an orthogonal, 2 step, diagnostic testing algorithm that employs a first line test for antibodies against nucleocapsid (N) protein. If anti-N antibodies are detected, then the sample is reflexively tested for anti-S protein antibodies. If the anti-N antibody test is negative then the results are reported as negative. If both anti-N and anti-S antibodies are detected, then the results are reported as positive. If anti-N antibodies are detected and no anti-S antibodies are detected, then the results are reported as discordant and the patient may consider re-testing in 7 to 14 days. This is the best test for diagnosis of COVID-19 or immunity following natural infection because it maximizes the sensitivity and specificity of serological testing.
Both the anti-N and anti-S protein antibody tests are qualitative, not quantitative tests, but quantitative tests are on the horizon that may be better able to assess antibody levels.