Administration of live varicella vaccine to children wtih leukaemia

Live varicella vaccine was given to twenty-three children with lymphoreticular malignancies, twelve whose chemotherapy was complete and eleven who were still receiving therapy. Seroconversion was observed in all twenty-three children, only one of whom lost his vaccine-induced antibody. Eight of the children experienced thirteen exposures to varicella, including four continuing exposures in their households. Varicella, manifested by the appearance of seven vesicular lesions, developed in only one. In all but two of the children an invitro blastogenic response to varicella/zoster-virus (VZV) antigen developed; both children had a biphasic rash after immunisation. A sibling of one of these children seroconverted without clinical evidence of varicella, presumably because of infection with vaccine virus. None of the other household contacts had significant rises in VZV antibody. VZV was not isolated from the blood, throat, or urine samples of the twenty-three vaccinees tested.