IMMUNOGENICITY AND SAFETY OF HAEMOPHILUS- INFLUENZAE TYPE-B POLYSACCHARIDE-TETANUS PROTEIN CONJUGATE (PRP-T) VACCINE IN CHILDREN WITH SICKLE-CELL DISEASE

Background. Infants and young children with sickle cell anemia are at increased risk of infection with Haemophilus influenzae type b. This r eport describes the immunogenicity and safety of Haemophilus b conjuga te vaccine in such children. Population and methods. One hundred and e leven children aged 6 months - 11 years (mean: 3.7 years) were studied . They belonged to a cohort of over 600 children in the Paris area tha t have sickle cell anemia. After parental consent, they were given one injection (intramuscularly or subcutaneously) of Haemophilus influenz ae type b-tetanus toxoid conjugate vaccine (0.5 ml). Any adverse react ions during the following 3 days were noted. Titers of specific antibo dies were measured just before injection, one month, and one year late r. Result. The vaccine was well tolerated, with only local reactions: erythematous reactions in 5 children and pain in 30. In the children a ged 6 months - 3 years, the mean antibody titers increased from 0.09 t o 20.6 mug/ml, 1 month after the vaccination; in those aged 3-11 years , the mean titer increased from 0.44 to 56.86 mug/ml. One year after v accination, the titers measured in 61 children were over 1 mug/ml in 9 2% of children aged 6 months -3 years and in 100% of the older childre n. Conclusion. This type of vaccine is immunogenic and well tolerated. Thus the vaccination schedule recommended for children with sickle ce ll anemia aged over 6 months is the same as that for normal children.