- Zerboni L,
- Nader S,
- Aoki K,
- Arvin AM
Purpose of the Study
To evaluate the persistence of humoral and cellular immunity to varicella-zoster virus (VZV) in children and adults immunized with live attenuated VZV vaccine.
Two hundred healthy children (ages 2–12 years) and forty healthy adults (ages 13–45 years) were vaccinated and identified as seroconverters who did not develop breakthrough varicella. Of these individuals, 60 children and 18 adults agreed to be reevaluated.
Serum was collected at the time of vaccination and then serially for 5 years postvaccination. The presence of anti-VZV IgG antibodies was determined by enzyme-linked immunosorbent assay (ELISA) and cell-mediated immunity to VZV was detected by lymphocyte proliferation assay. Peripheral blood mononuclear cells were stimulated with VZV antigen and supernatents were then assayed for interleukin-2, interferon-gamma, and interleukin-10 response.
At a mean of 5 years after vaccination, 93% of children and 94% of adults had immunoglobulin G (IgG) antibodies to VZV as determined by ELISA. VZV antibody concentrations were significantly higher at 5 years than at 1 year after immunization in children and adults. Cell-mediated immunity to VZV was detected in 87% of children and 94% of adults at 5 years. The mean stimulation index was significantly higher at 5 years than at 1 year among children and adults. Cytokine responses to VZV, including interleukin-2, interferon-gamma, and interleukin-10 were equivalent between children and adults at 5 years.
Varicella immunization induced long-term humoral and cellular immunity, and initial differences between cell-mediated responses in children and adults diminished over time.
As more of the population receives the varicella vaccine, the opportunities for exogenous exposure to wild-type VZV will decrease. It is unclear if these exposures are a major mechanism for preserving immunity to VZV, but if so, then it may be necessary to boost immunity with the varicella vaccine at some future point. However, at 5 years, both humoral and cellular immunity appear to be intact.