title: Natural and vaccine-induced immunity against Haemophilus influenzae type b in patients with beta-thalassemia.
abstract: Natural and vaccine-induced immunity and immunological memory to Haemophilus influenzae type b (Hib) were evaluated in adolescents and adults with beta-thalassemia. At baseline 10/23 (43%) unvaccinated patients had naturally acquired anticapsular antibodies >0.15 microg/ml, the threshold of protection, compared to 9/10 (90%) aged-matched controls. Hib-conjugate vaccine (PRP-T) induced protective immune responses in all subjects and there were no differences in geometric mean concentrations at 1 month (GMC) between patients and controls (69.04 versus 40.5, respectively). Vaccine-induced immunological memory was assessed in 12 subjects with beta-thalassemia who had been vaccinated against Hib in the past. All subjects had retained PRP>1 microg/ml at baseline; PRP-T revaccination induced anamnestic responses which were similar, in terms of post vaccination antibody concentration (P=0.54) and avidity (P=0.08), with primary responses given by previously unvaccinated patients. A single dose of PRP-T induces adequate and long-lasting immunity and should be given in all unvaccinated adolescents and adults with beta-thalassemia.
authors.affiliation: 1st Department of Paediatrics, Division of Infectious Diseases, Aghia Sophia Children's Hospital, Athens University School of Medicine, Athens, Greece. vspoulou@cc.uoa.gr
authors.forename: Vana I
authors.initials: VI
authors.lastname: Spoulou
authors.forename: Dimitris L
authors.initials: DL
authors.lastname: Tsoumas
authors.forename: Vasilis
authors.initials: V
authors.lastname: Ladis
authors.forename: Ageliki
authors.initials: A
authors.lastname: Spentzou
authors.forename: Maria C
authors.initials: MC
authors.lastname: Theodoridou
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood; D000915:Antibody Affinity; D016667:Bacterial Capsules / Q000276:immunology; D016022:Case-Control Studies; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018073:Haemophilus Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D019741:Haemophilus influenzae type b / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007156:Immunologic Memory; D008297:Male; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage* / Q000276:immunology*; D017086:beta-Thalassemia
chemical_list: D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial