[Immunogenicity and tolerability of Haemophilus b-tetanus protein conjugate (PRP-T) in children with sickle cell anemia].

Background: Infants and young children with sickle cell anemia are at increased risk of infection with Haemophilus influenzae type b. This report describes the immunogenicity and safety of Haemophilus b conjugate vaccine in such children.

Population and methods: One hundred and eleven 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 that have sickle cell anemia. After parental consent, they were given one injection (intramuscularly or subcutaneously) of Haemophilus influenzae type b-tetanus toxoid conjugate vaccine (0.5 ml). Any adverse reactions during the following 3 days were noted. Titers of specific antibodies were measured just before injection, one month, and one year later.

Results: The vaccine was well tolerated, with only local reactions: erythematous reactions in 5 children and pain in 30. In the children aged 6 months-3 years, the mean antibody titers increased from 0.09 to 20.6 micrograms/ml, 1 month after the vaccination; in those aged 3-11 years, the mean titer increased from 0.44 to 56.86 micrograms/ml. One year after vaccination, the titers measured in 61 children were over 1 microgram/ml in 92% of children aged 6 months-3 years and in 100% of the older children.

Conclusion: This type of vaccine is immunogenic and well tolerated. Thus the vaccination schedule recommended for children with sickle cell anemia aged over 6 months is the same as that for normal children.