title: Long-lasting immunogenicity of a virosomal vaccine in older children and young adults with type I diabetes mellitus.
abstract: To evaluate the long-lasting immunogenicity and reactogenicity of a virosomal influenza vaccine in subjects with type I diabetes, a trial was conducted during the 2007-2008 influenza season in Milan, Northern Italy. One hundred five subjects aged 9-30 years were randomized to receive by intramuscular injection vaccination by a single dose (0.5 ml) of either a virosomal (Inflexal V) (n=52) or a standard subunit (Influvac) (n=53) vaccine. Serum hemagglutinin inhibition antibody titres were determined against the three recommended influenza-like strains, A/H1N1, A/H3N2 and B, at pre-vaccination, and 1 and 6 months post-vaccination. Geometric mean titres were increased in the two groups 1 and 6 months post-vaccination (P<0.001). One month post-vaccination both vaccines met the CPMP requirement for immunogenicity with high seroprotection rates (>95%) for strains A/H1N1 and A/H3N2, and a seroprotection of 73% and 70% in the virosomal and subunit vaccine for strain B. Mean fold increase ranged 2.8 (A/H3N2)-6.2 (A/H1N1) in the virosomal group and 2.3 (A/H3N2)-4.8 (A/H1N1) in the subunit group. Immunogenicity declined 6 months post-vaccination in both groups, and the CPMP requirement for immunogenicity was satisfied only in the virosomal group. In subjects without pre-existing antibodies to strain B (titre <10), the virosomal vaccine showed higher immune response than the subunit vaccine 6 months post-vaccination, with a geometric mean titre (95% CI) of 40.2 (30.7-54.6) vs. 21.2 (14.6-30.8). Reactogenicity was similar in the two vaccines. All reactions were transient and not severe. The results indicate that in older children and young adults with type I diabetes influenza vaccination with a virosomal or a standard subunit vaccine is safe and adequately immunogenic against the three influenza vaccine strains. In addition, the virosomal vaccine may show better long-lasting immune response than the standard subunit vaccine, especially in subjects without pre-existing antibodies to influenza strains.
authors.affiliation: Department of Pediatrics, University of Milan, Luigi Sacco Hospital, 20157 Milan, Italy. gianvincenzo.zuccotti@unimi.it
authors.forename: Gian Vincenzo
authors.initials: GV
authors.lastname: Zuccotti
authors.forename: Andrea
authors.initials: A
authors.lastname: Scaramuzza
authors.forename: Sara
authors.initials: S
authors.lastname: Riboni
authors.forename: Chiara
authors.initials: C
authors.lastname: Mameli
authors.forename: Elena
authors.initials: E
authors.lastname: Pariani
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Tanzi
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zanetti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Radaelli
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D004311:Double-Blind Method; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D011446:Prospective Studies; D022721:Vaccines, Virosome / Q000008:administration & dosage / Q000276:immunology; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines; D022721:Vaccines, Virosome