Human immune responses to live attenuated varicella vaccine

Experiences with the use of the live attenuated varicella vaccine for the immunization of varicella-susceptible adults and healthy and leukemic children are described. Healthy children, for whom a greater than 90% rate of seroconversion and protective efficacy was noted, showed the best response. Leukemic children experienced a 40%-50% rate of vaccine-associated rash; protective efficacy approached 90%. For adults, a 10% rate of vaccine-associated rash and a protective efficacy of 70% were noted. Breakthrough cases of vaccine were mild, indicating modification of the course of the illness by the vaccine.