title: Antibodies against Haemophilus influenzae type b in The Gambia: investigating the extent of protection across age groups.
abstract: Following a landmark clinical trial, the vaccine against Haemophilus influenzae type b (Hib) was introduced in The Gambia in 1997. Whilst the immunogenicity of this vaccine is well established subsequent to the doses administered under the EPI schedule, little data exists assessing longevity of protection, using serology. Such data are needed however to predict the susceptibility to Hib at the population level. To determine antibody persistence in 5-6 year old fully vaccinated Gambian children compared with older children, adolescents and young adults, 427 serum samples from healthy 5-37 year old participants were tested for Hib antibodies using VaccZyme Human Anti-Hib ELISA kits. 86% of the children who had received 3 doses of Hib vaccine in infancy had Hib antibody concentrations ≥0.15 mg/l at the age of 5-6 years. This proportion was 76% for adolescents who had also largely been vaccinated and 90% for adults who had never received Hib vaccine. Although most participants had anti-Hib antibody above concentrations putatively defined as protective, significantly fewer had concentrations thought to confer long-term protection. This suggests a population with insufficient or waning antibody that may be susceptible to breakthrough disease and transmission.
authors: Medical Research Council Unit, The Gambia. Electronic address: oidoko@mrc.gm.
authors: O T
authors: OT
authors: Idoko
authors: Medical Research Council Unit, The Gambia.
authors: E
authors: E
authors: Roberts
authors: Medical Research Council Unit, The Gambia.
authors: M
authors: M
authors: Cox
authors: Medical Research Council Unit, The Gambia.
authors: J
authors: J
authors: Jafali
authors: Medical Research Council Unit, The Gambia.
authors: J
authors: J
authors: Njie-Jobe
authors: Medical Research Council Unit, The Gambia; Murdoch Children's Research Institute, Melbourne, Australia.
authors: G
authors: G
authors: Mackenzie
authors: WHO Regional Office for Africa, Brazzaville, Congo.
authors: M O
authors: MO
authors: Ota
authors: Medical Research Council Unit, The Gambia; Academic Department of Paediatrics, Imperial College London, London W2 1NY, UK.
authors: B
authors: B
authors: Kampmann
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000097:blood; D016667:Bacterial Capsules; D002648:Child; D002675:Child, Preschool; D005260:Female; D005714:Gambia / Q000453:epidemiology; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000517:prevention & control; D018073:Haemophilus Vaccines / Q000627:therapeutic use; D019741:Haemophilus influenzae type b; D064368:Healthy Volunteers; D006801:Humans; D007115:Immunization Schedule; D008297:Male; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine
keywords: Antibody; Gambia; Hib vaccine; Protection