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Immunogenicity of Haemophilus influenzae-diphtheria CRM197 protein conjugate vaccine (HbOC) in Libyan infants
M Hadida1, L E Cuevas, A Moghadami
1Tropical Microbiology Centre, Division of Tropical Medicine, Liverpool School of Tropical Medicine, UK.
Insights
The Haemophilus influenzae type b conjugate vaccine (HbOC) demonstrated strong immunogenicity and safety in Arab children, similar to findings in industrialized nations. High antibody levels suggest effective protection, even after two doses.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Haemophilus influenzae type b (Hib) infections pose a significant health risk, particularly in young children.
- Conjugate vaccines like HbOC are crucial for preventing Hib disease.
Purpose of the Study:
- To evaluate the immunogenicity and safety of the HbOC vaccine in Arab children in Tripoli.
- To compare antibody levels in infants receiving HbOC with those who did not.
Main Methods:
- A randomized clinical trial involving 90 infants receiving HbOC with other routine vaccines (Hepatitis B, OPV, DPT) at 2, 3, and 4 months.
- Comparison group of 81 infants receiving routine vaccines without HbOC.
- Measurement of anti-Hib antibody levels after one, two, and three doses.
Main Results:
- HbOC vaccine showed high immunogenicity and safety, comparable to industrialized countries.
- Fever and local discomfort occurred in less than 2% of infants.
- Significant increase in anti-Hib antibodies after the first dose, with geometric mean levels of 0.41, 1.36, and 2.91 mg/ml after one, two, and three doses, respectively.
- After two doses, all infants achieved antibody levels above 0.20 mg/ml, with the lowest concentration at 0.80 mg/ml.
Conclusions:
- The HbOC vaccine is immunogenic and safe in Arab children, yielding antibody levels similar to those in Europe and the USA.
- High antibody titers suggest that HbOC provides good clinical protection in this population, potentially even after two doses.
- The findings support the routine use of HbOC for Hib prevention in this region.
Abstract:
The immunogenicity of the HbOC, a Haemophilus influenzae type b conjugate vaccine, was evaluated in a randomized clinical trial of Arab children resident in Tripoli. The HbOC vaccine was given as part of a three-dose series at 2, 3 and 4 months of age together with hepatitis B, OPV and DPT to 90 children. Anti-H. influenzae antibody levels were compared with 81 infants receiving hepatitis B, OPV and DPT but not the HbOC vaccine. The immunogenicity and safety of HbOC was as high as that observed in industrialised countries. There were no major complications, and fever and temporary local discomfort were observed in fewer than approximately 2% of the infants. Infants receiving the HbOC vaccine had an increase in Hib antibodies with only one dose. Geometric mean anti-Hib antibody levels were 0.41, 1.36 and 2.91 mg/ml after one, two and three doses. After two doses, all children had antibody levels above 0.20 mg/ml and the lowest antibody concentration was 0.80 mg/ml. Antibody levels in our children are similar to those observed in Europe and the USA and it is thus likely that HbOC will provide good clinical protection in this population. As most of the children develop antibody titres above or near 1 mg/ml, it is likely that they are protected even with two doses of the vaccine. The anti-Hib antibody levels observed are similar to those in studies from Europe where hepatitis B vaccine is not routinely given.