University HealthCare Alliance

April 16, 2020

Stanford Lab Offering COVID-19 Serology Tests

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.

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