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Antibody responses to Haemophilus influenzae type b conjugate vaccine in sickle cell disease
D Goldblatt1, M Johnson, J Evans
1Immunobiology Unit, Institute of Child Health, London.
Insights
Children with sickle cell disease over age 2 mounted a strong antibody response to the Haemophilus influenzae type b (Hib) conjugate vaccine. Unimmunized children with sickle cell disease should receive a single Hib vaccine dose.
Area of Science:
- Immunology
- Pediatrics
- Vaccinology
Background:
- Sickle cell disease (SCD) compromises immune function, increasing susceptibility to infections.
- Haemophilus influenzae type b (Hib) is a significant pathogen in children with SCD.
- Assessing vaccine immunogenicity in vulnerable populations is crucial for public health.
Purpose of the Study:
- To evaluate the immune response to Haemophilus influenzae type b (Hib) conjugate vaccines in children diagnosed with sickle cell disease.
- To determine if a single dose of Hib vaccine elicits adequate antibody levels for protection in this population.
Main Methods:
- An open-label study was conducted at a hemoglobinopathy clinic.
- Children over 2 years with sickle cell disease (HbSS, HbSC, HbS-beta Thal) received a single dose of Hib-tetanus toxoid conjugate vaccine (PRP-T).
- Antibody response to Hib polysaccharide (PRP) was measured approximately one month post-vaccination.
Main Results:
- 77 children with SCD (55 HbSS, 16 HbSC, 6 HbS-beta Thal) were studied.
- Prior to vaccination, 44% had suboptimal anti-PRP IgG levels.
- Following a single PRP-T dose, all children achieved protective anti-PRP IgG titres (>1 microgram/ml), with geometric mean titres comparable to healthy populations.
Conclusions:
- Children over 2 years with sickle cell disease demonstrate a robust antibody response to a single dose of the Hib conjugate vaccine (PRP-T).
- These findings support the recommendation for a single dose of Hib conjugate vaccine in unimmunized children with sickle cell disease.
- The study highlights the importance of timely vaccination in immunocompromised pediatric populations.
Objective:
To investigate the immunogenicity of Haemophilus influenzae type b (Hib) conjugate vaccines in children with sickle cell disease.
Design:
Open study.
Setting:
Haemoglobinopathy clinic.
Subjects:
Children with homozygous haemoglobin SS disease (HbSS), sickle haemoglobin C disease (HbSC), and sickle-beta thalassaemia disease (HbS-beta Thal).
Interventions:
Children over the age of 2 years received a single dose of Hib-tetanus toxoid conjugate vaccine (PRP-T).
Main Outcome Measures:
Antibody response to Hib polysaccharide (PRP) approximately one month after vaccination.
Results:
77 children over the age of 2 years were studied,, 55 with HbSS, 16 with HbSC, and six with HbS-beta Thal. Before vaccination, 44% had anti-PRP IgG titres less than the level associated with long term protection (1.0 microgram/ml). After a single dose of PRP-T all children mounted an antibody titre > 1 microgram/ml. Geometric mean anti-PRP IgG titre achieved postvaccination (45.2 micrograms/ml 95% confidence interval (CI) 31.6 to 64.8) was comparable to that of a healthy population. Children with HbSC, however, had a significantly higher antibody titre postvaccination (91.1 micrograms/ml; 95% CI 32.7 to 254.4) than the children with HbSS (36.7 micrograms/ml; 95% CI 25.1 to 52.9).
Conclusions:
Children with a diagnosis of sickle cell disease who are over the age of 2 years make a vigorous antibody response to a single dose of PRP-T vaccine and hence we suggest unimmunised individuals in this group should receive a single dose of a Hib conjugate vaccine.