Varicella vaccine in non-immune household contacts of children with canceror leukaemia

Objective: To assess the immunogenicity and reactogenicity of a new formula tion of live attenuated varicella Vaccine (Oka strain) in non-immune househ old contacts of children with cancer or leukaemia. Methodology: This was an open study with one group. Healthy varicella-susce ptible adults and children living in the same household as children with ca ncer or leukaemia were vaccinated with a new live attenuated varicella Vacc ine (Oka strain) which is stable when stored at 2-8 degrees C (refrigerator temperature) for at least 24 months (Varilrix). Children less than 13 year s of age received one dose (0.5 mL containing at least 10(3.3) plaque formi ng units) by subcutaneous injection and those aged over 13 years received t wo doses 8 weeks apart. Adverse reactions following vaccination were record ed daily by the vaccinees. Post-vaccination antibody estimation was determi ned using indirect immunofluorescence 6 weeks after vaccination. Results: Thirty-five seronegative subjects (28 children and 7 adults and ad olescents) were vaccinated. All subjects tested (34) had seroconverted afte r vaccination. Local injection site reactions were experienced by 15/35. Ot her adverse reactions were uncommon (rash 2/35, fever (greater than or equa l to 37.5 degrees C) 3/35). No cases of clinical varicella occurred amongst the high-risk household contacts of the vaccine. Conclusion: This is the first study of this formulation of varicella Vaccin e in household contacts of children with cancer or leukaemia. The Vaccine w as found to be safe and immunogenic, but further follow-up is needed to doc ument duration of immunity.