Varicella vaccine in immunocompromised children was clinically evaluated in 575 US and Canadian children with
leukemia in remission by the
Varicella Vaccine Collaborative Study. Most children had
chemotherapy stopped 1 week before and 1 week after immunization.
Steroids were stopped for 3 weeks (1 week before to 2 weeks after vaccination).
Varicella vaccine was safe, immunogenic, and effective in leukemic children at risk for serious disease or death from
chickenpox. The major side effect was mild
rash in 50% approximately 1 month after immunization. About 40% of children who developed
rash were treated with
acyclovir.
Vaccine efficacy was judged by the degree of protection after a household exposure to
varicella; of 123 exposed children, 17 (14%) developed a mild form of
varicella. The
vaccine protected completely against severe
varicella. Leukemic
vaccines were less likely to develop
zoster than were comparable children with
leukemia who had wild type
varicella. Thus,
varicella vaccine, administered carefully with close follow-up, is extremely beneficial for leukemic children.