Vaccination of children with malignant disease against varicella.

Nineteen seronegative children and one young adult with malignant disease in remission and on maintenance chemotherapy were immunized with the Oka-strain live attenuated varicella vaccine (Varilrix). Side effects were moderate and a rash was seen in 50% of the patients after vaccination. Humoral immune response to the vaccine was tested by the fluorescent antibody to membrane antigen (FAMA) test, a simpler indirect immunofluorescence test (IFT), and an enzyme-linked immunosorbent assay (ELISA). The seroconversion rate after immunization varied according to the method used. Seven out of 8 responded by FAMA, 15 out of 20 by IFT, and 12 out of 20 by ELISA. A decline in post-vaccination varicella-zoster virus (VZV) antibodies was seen in some responders. In 2 children, detectable levels of passively transferred VZV antibodies at the time of vaccination, due to varicella-zoster immune globulin, may have interfered with or modified the response to the vaccine. Cross-reacting antibodies to herpes simplex virus may have possibly interfered with vaccine response in a third child. Six out of 8 children receiving a second vaccine dose showed a good serological response. Specific cell-mediated immune response to the vaccine, measured by lymphocyte proliferation tests, corresponded well with the humoral response in the initial study of 8 patients. Two children who had responded to the vaccine were exposed to varicella in their families without contracting the clinical disease.