From the Guidelines
A normal varicella zoster titer level is typically considered to be $5 gpELISA units per mL or higher, as indicated by studies using the FAMA assay, which correlates with protection against disease. When interpreting varicella zoster virus (VZV) antibody titers, it's essential to consider the context of the individual's immune status and potential exposure to the virus.
- The presence of antibodies against VZV, as measured by gpELISA units per mL, indicates previous exposure to the virus through either natural infection or vaccination 1.
- A titer of $5 gpELISA units per mL or higher is generally considered protective against varicella, with fewer than 1% of healthy persons achieving a titer of 1:4 developing varicella after a household VZV exposure 1.
- The administration of 2 doses of monovalent varicella vaccine 3 months apart initially produces a higher geometric mean titer, compared with 1 dose of vaccine, and a larger percentage of patients who receive 2 doses have initial antibody concentrations of $5 gpELISA units per mL 1.
- It's crucial to note that humoral and cellular immunity are important for viral clearance and for protection against reinfection or reactivation of latent VZV, and that cellular immunity after 2 doses of varicella vaccine is more robust than that after 1 dose of vaccine 1.
- In clinical practice, healthcare workers, pregnant women, and immunocompromised individuals often need to know their immunity status, and a positive titer can provide reassurance of protection against chickenpox.
From the Research
Normal Varicella Zoster Titer Level
- The normal varicella zoster titer level can be determined by various methods, including radioimmunoassay and indirect immunofluorescence 2.
- A study found that the geometric mean titer of VZV-specific IgG was 1:6,309, and titers were greater than or equal to 1:16,384 in 20 subjects who had had varicella at least 20 years before testing 2.
- The VZV radioimmunoassay provided a sensitive and practical method for measuring VZV IgG and IgM antibodies, with high titers of VZV IgM antibody detected in unfractionated sera despite the presence of high titers of VZV IgG antibody 2.
- Another study discussed the immune responses to varicella-zoster virus vaccines, but did not provide specific information on normal titer levels 3.
- A more recent study discussed the varicella vaccine and its efficacy, but also did not provide specific information on normal titer levels 4.
- A study on gastric emptying and secretion in the rhesus monkey is not relevant to varicella zoster titer levels 5.