A DOSE-RESPONSE STUDY OF A LIVE ATTENUATED VARICELLA-ZOSTER VIRUS (OKA STRAIN) VACCINE ADMINISTERED TO ADULTS 55 YEARS OF AGE AND OLDER

Decreased cell-mediated immune (CMI) response to varicella-zoster viru s (VZV) is correlated with an increased risk of reactivation of latent virus from dorsal root sites, leading to herpes tester. The cell-medi ated and humoral immunogenicity of three concentrations (3200, 8500, a nd 41,650 pfu/dose) of a live attenuated VZV vaccine (Oka strain; VZV/ Oka) was compared with a control pneumococcal polysaccharide vaccine i n 200 healthy adults who were greater than or equal to 55 years old. S ix weeks after vaccination, the VZV-specific CMI response las measured by stimulation index values and precursor cell frequencies) was enhan ced in all VZV/Oka vaccine groups compared with the control group (for all VZV/Oka groups combined vs. controls, tested with VZV crude antig en: stimulation index, P < .001; precursor cell frequency, P < .001). Geometric mean titers of anti-VZV antibodies increased in all VZV/Oka vaccine groups but remained unchanged in the control vaccine group. No dose effect of VZV/Oka vaccine was observed for CMI or humoral respon ses.