Related Experiment Videos
Haemophilus influenzae type b immunization of children with sickle cell diseases
A L Frank1, R J Labotka, S Rao
1Department of Pediatrics, University of Illinois, College of Medicine, Chicago 60612.
Insights
The Haemophilus influenzae type B vaccine (PRP-D) showed better immunogenicity than the PRP vaccine in children with sickle cell disease. PRP-D is more effective in eliciting protective antibody levels against Hib.
Area of Science:
- Pediatric Immunology
- Vaccinology
- Hematology
Background:
- Haemophilus influenzae type B (Hib) vaccination is recommended for children with sickle cell disease.
- The immune response adequacy to Hib vaccines in this vulnerable population remains unclear.
- Sickle cell disease patients may have altered immune responses to standard vaccination protocols.
Purpose of the Study:
- To compare the immunogenicity of two Haemophilus influenzae type B vaccines in children with sickle cell syndromes.
- To evaluate the safety and efficacy of PRP vaccine versus PRP-D vaccine in this specific pediatric group.
- To determine antibody response levels post-immunization in children with sickle cell anemia.
Main Methods:
- A single-blind study involving 69 children (1.5–5.6 years) with sickle cell syndromes.
- Children were randomized to receive either PRP vaccine (n=36) or PRP-D vaccine (n=36).
- Anti-PRP antibody levels were measured using radioimmunoassay pre- and post-vaccination.
Main Results:
- Both vaccines were safe, with frequent minor reactions reported.
- PRP-D demonstrated significantly higher geometric mean titers (15.58 µg/mL) and mean fold increases (234-fold) compared to PRP (2.63 µg/mL, 29-fold).
- 94% of children receiving PRP-D achieved protective antibody levels (≥1.0 µg/mL) versus 64% receiving PRP.
Conclusions:
- Both PRP and PRP-D vaccines are useful for children with sickle cell syndromes.
- PRP-D vaccine is more immunogenic, inducing higher and more sustained antibody levels.
- Further research is needed on long-term antibody levels, booster responses, and immunogenicity in younger children.
Abstract:
Haemophilus influenzae type B vaccine is recommended for children 1.5 to 6 years of age with sickle cell anemia, but the adequacy of their response is unknown. A total of 69 children with sickle cell syndromes, 1.5 to 5.6 years of age, were immunized with two vaccines alternatively, single blind. PRP vaccine was given to 36 children and a diphtheria toxoid conjugated vaccine, PRP-D, was given to 36. Coded pre- and postvaccine sera were tested by radioimmunoassay for anti-PRP antibody. The groups did not differ in age distribution or type of sickle hemoglobinopathy. Preexisting antibody levels were low in both vaccine groups; 65% were less than 0.15 microgram/mL. The vaccines were safe but associated with frequent minor reactions. PRP-D gave higher geometric mean titers and mean fold titer increase than PRP in all children (15.58 micrograms/mL [234-fold] v 2.63 micrograms/mL [29-fold]) and in the subgroups 1.5 to 2.5 years of age or with pretiter values less than 0.15 microgram/mL. Titers for 64% of children receiving PRP and 94% receiving PRP-D were greater than or equal to 1.0 microgram/mL. Thus, both vaccines were useful in this population, but PRP-D was more immunogenic. Duration of antibody levels postvaccination, booster responses, and PRP-D immunogenicity in younger children with sickle cell syndromes all require further study.