What laboratory tests are available to determine varicella immunity prior to vaccination?
The most common commercially available test is the EIA (enzyme immunoassay). This test is sensitive enough to determine immunity following natural disease, but may not be sensitive enough for determining immunity following vaccination when antibody levels are lower. The serology test used to determine immune response to varicella vaccine during the clinical trails, the gpELISA test, is not available commercially. Thus, serological results obtained following vaccination must be interpreted with caution since some commercially available tests are not sensitive enough to detect low levels of antibody post-vaccination. Other tests with higher sensitivity than the commercially available EIA such as the FAMA (flourescent antibody-to-membrane antigen) assay requires extensive experience and is performed only in a few academic laboratories. A VZV latex bead agglutination assay is now commercially available that is more sensitive than most conventional EIAs.
