Analysis of the Persistence of Humoral and Cellular Immunity in Children and Adults Immunized with Varicella Vaccine

The persistence of humoral and cellular immunity to varicella-zoster virus (VZV) was evaluated in 60 children and 18 adults immunized with live attenuated VZV vaccine. At a mean of 5 years after vaccination, 93% of children and 94% of adults had 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. In summary, varicella immunization induced long-term humoral and cellular immunity, and initial differences between cell-mediated responses in children and adults diminished over time.