ANTIBODY KINETICS IN CHILDREN WITH HEMOPHILIA IMMUNIZED WITH INFLUENZA VACCINE IN 1993 IN POLAND

Fifty-one children with hemophilia, 7 to 16 years of age, were vaccina ted subcutaneously with a single dose of trivalent inactivated influen za vaccine in the Department of Hematology and Oncology, Medical Acade my, in Warsaw at the end of 1993. Serum antibody levels in vaccinees a nd in a control unvaccinated group were monitored before vaccination a nd then 3 weeks and 6 months after vaccination by using the hemaggluti nin inhibition (HI) and neuraminidase inhibition (NI) tests. Results w ere evaluated as geometric mean titer (GMT), mean fold antibody increa se (MFI), percentage of subjects with an HI antibody titer of 1:40 or greater and seroconversion rates for HI antibody titers and as GMT and MFI for NI antibody titers. After vaccination, the proportion of vacc inees with HI antibody titers greater than or equal to 40 ranged betwe en 71 and 94%. In the control group the GMTs for HI hemagglutinin (HA) were consistently low and for the H3 subtype and type B HA the GMT de clined at the 6-month time point compared with the original value. Thr ee weeks after vaccination the GMT for N1 neuraminidase (NA) was 12.7 times higher than before vaccination, while for N2 NA it was 15.9 time s higher and for type B NA it was 9.8 times higher than before vaccina tion. In the control group GMT values were low for all NA antigens. Su bcutaneous vaccination, necessary to prevent bleeding, did not prevent an immunologic response. Vaccine was well tolerated. The results demo nstrate high rates of seroconversion for both the HA and NA components of influenza vaccine after vaccination when compared with the control unvaccinated group.