Active immunization against varicella of children with acute leukaemia or other malignancies on maintenance chemotherapy.

Twenty-six patients with acute leukaemia and other malignancies susceptible to varicella were vaccinated with the Oka-strain live attenuated varicella vaccine during maintenance chemotherapy. All recipients showed no adverse clinical reactions. There was no spread of vaccine virus. Seroconversion was 94% in seronegative patients. Among those having low antibody titres before vaccination, a booster effect was demonstrable in 56%. None of the seroconverted recipients contracted varicella despite documented contact exposure. No case of herpes zoster occurred. The results suggest that, in immunocompromised children, live varicella vaccination has a protective effect against varicella infection which may result in a mortality rate of up to 7% in these patients.