The Stanford Clinical Laboratory is offering a COVID-19 serology test that detects IgG & IgM antibodies
to the SARS CoV-2 spike receptor binding domain (RBD). This laboratory-developed test has been
validated using plasma from confirmed COVID-19 infected individuals. When ordering a COVID-19
serology test, it is important to understand the limitations.
- The presence of IgM, IgG, and/or IgA antibodies indicates an immune response to COVID-19 but
it is not known at this time if the response is protective against future infections. - False positive results are possible in serology assays; it is unclear what rate of false positive
results will occur in individuals with recent infection by other kinds of coronaviruses, or other
inflammatory conditions. - The absence of IgM, IgG, or IgA antibodies does not exclude COVID-19 infection. It can take 1-2
weeks after onset of symptoms for antibodies to develop. - The results of a COVID-19 serology test should not guide PPE use or other infection control
measures, i.e. a health care worker with a positive COVID-19 serology test should not decrease
PPE use. - This is a billable test.
Obtain a nasopharyngeal swab for SARS-CoV-2 PCR to evaluate for the possibility of an active COVID-19
infection, if COVID-19 serology is positive or if the patient is symptomatic (regardless of serology result).
The Stanford COVID-19 serology test is a plate-based enzyme-linked immunosorbent assay (ELISA)
performed in a high complexity lab. It is distinct from the rapid serology tests (lateral flow immunoassay)
performed on a finger-stick blood sample. Many of the rapid blood serology tests have not been fully validated and the performance characteristics are not well established.