Responses of varicella zoster virus (VZV)-specific immunity in seropositive adults after inhalation of inactivated or live attenuated varicella vaccine

To examine boostering of varicella zoster virus (VZV)-specific immunity in seropositive adults after nasal inhalation of heat-inactivated or live attenuated varicella vaccine, we determined specific cellular immunity, IgG antibody in sera and secretory IgA antibody in saliva before and after the inhalation. The mean titers in specific IgG antibody and skin test findings significantly increased following inhalation of both vaccines. However, the ratio of a two-fold or more increase in the levels of IgG antibody or skin test did not show significant difference after inhalation of the inactivated vaccine in comparison with those in the control. After inhalation of the live vaccine, the ratio showed significant difference but transmission of the live vaccine virus to others was suspected. No significant increase in VZV-secretory IgA antibody levels in saliva was noted following inhalation. The results of this study suggested that nasal inhalation of the live vaccine could increase specific immunity in adults. This method would be similar to the natural infection and simpler than subcutaneous injection.