Re-immunisation schedule in leukaemic children after intensive chemotherapy: a possible strategy.

The aim of this retrospective study was to test the residual humoral immunity to compulsory vaccines after the end of chemotherapy for acute lymphoblastic leukaemia in a cohort of 70 Italian children. All the patients, who had been immunised according to the Italian schedule prior to the disease, were tested for antibody levels against tetanus and hepatitis B at a median of 10 months after the end of therapy. Median age at diagnosis of leukaemia was 48 months, and median age at vaccine titration was 84 months. The protective level of antibodies for tetanus and hepatitis B was shown in 83% and 81% of patients, respectively; the remaining 17% and 19% were not protected against the two pathogens. Double negativity was observed in only four of 62 (6%) patients in the cohort. These data were comparable with published data regarding healthy children of the same age and from the same geographical areas. Therefore, given the direct and indirect costs of performing laboratory tests, as well as the cost of revaccination, our proposal is to continue the vaccination schedule according to the child's age without any titration screening 6 months after the end of therapy. Larger studies are needed to confirm these observations.