title: Immunogenicity and safety of a meningococcal A conjugate vaccine in Africans.
abstract: BACKGROUND
  Group A meningococci are the source of major epidemics of meningitis in Africa. An affordable, highly immunogenic meningococcal A conjugate vaccine is needed.
  
  
  METHODS
  We conducted two studies in Africa to evaluate a new MenA conjugate vaccine (PsA-TT). In study A, 601 children, 12 to 23 months of age, were randomly assigned to receive PsA-TT, a quadrivalent polysaccharide reference vaccine (PsACWY), or a control vaccine (Haemophilus influenzae type b conjugate vaccine [Hib-TT]). Ten months later, these children underwent another round of randomization within each group to receive a full dose of PsA-TT, a one-fifth dose of PsACWY, or a full dose of Hib-TT, with 589 of the original participants receiving a booster dose. In study B, 900 subjects between 2 and 29 years of age were randomly assigned to receive PsA-TT or PsACWY. Safety and reactogenicity were evaluated, and immunogenicity was assessed by measuring the activity of group A serum bactericidal antibody (SBA) with rabbit complement and performing an IgG group A-specific enzyme-linked immunosorbent assay.
  
  
  RESULTS
  In study A, 96.0% of the subjects in the PsA-TT group and 63.7% of those in the PsACWY group had SBA titers that were at least four times as high as those at baseline; in study B, 78.2% of the subjects in the PsA-TT group and 46.2% of those in the PsACWY group had SBA titers that were at least four times as high as those at baseline. The geometric mean SBA titers in the PsA-TT groups in studies A and B were greater by factors of 16 and 3, respectively, than they were in the PsACWY groups (P<0.001). In study A, the PsA-TT group had higher antibody titers at week 40 than the PsACWY group and had obvious immunologic memory after receiving a polysaccharide booster vaccine. Safety profiles were similar across vaccine groups, although PsA-TT recipients were more likely than PsACWY recipients to have tenderness and induration at the vaccination site. Adverse events were consistent with age-specific morbidity in the study areas; no serious vaccine-related adverse events were reported.
  
  
  CONCLUSIONS
  The PsA-TT vaccine elicited a stronger response to group A antibody than the PsACWY vaccine. (Funded by the Meningitis Vaccine Project through a grant from the Bill and Melinda Gates Foundation; Controlled-Trials.com numbers, ISRCTN78147026 and ISRCTN87739946.).
authors.affiliation: Centre pour le Développement des Vaccins, Bamako, Mali.
authors.forename: Samba O
authors.initials: SO
authors.lastname: Sow
authors.forename: Brown J
authors.initials: BJ
authors.lastname: Okoko
authors.forename: Aldiouma
authors.initials: A
authors.lastname: Diallo
authors.forename: Simonetta
authors.initials: S
authors.lastname: Viviani
authors.forename: Ray
authors.initials: R
authors.lastname: Borrow
authors.forename: George
authors.initials: G
authors.lastname: Carlone
authors.forename: Milagritos
authors.initials: M
authors.lastname: Tapia
authors.forename: Adebayo K
authors.initials: AK
authors.lastname: Akinsola
authors.forename: Pascal
authors.initials: P
authors.lastname: Arduin
authors.forename: Helen
authors.initials: H
authors.lastname: Findlow
authors.forename: Cheryl
authors.initials: C
authors.lastname: Elie
authors.forename: Fadima Cheick
authors.initials: FC
authors.lastname: Haidara
authors.forename: Richard A
authors.initials: RA
authors.lastname: Adegbola
authors.forename: Doudou
authors.initials: D
authors.lastname: Diop
authors.forename: Varsha
authors.initials: V
authors.lastname: Parulekar
authors.forename: Julie
authors.initials: J
authors.lastname: Chaumont
authors.forename: Lionel
authors.initials: L
authors.lastname: Martellet
authors.forename: Fatoumata
authors.initials: F
authors.lastname: Diallo
authors.forename: Olubukola T
authors.initials: OT
authors.lastname: Idoko
authors.forename: Yuxiao
authors.initials: Y
authors.lastname: Tang
authors.forename: Brian D
authors.initials: BD
authors.lastname: Plikaytis
authors.forename: Prasad S
authors.initials: PS
authors.lastname: Kulkarni
authors.forename: Elisa
authors.initials: E
authors.lastname: Marchetti
authors.forename: F Marc
authors.initials: FM
authors.lastname: LaForce
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Preziosi
mesh_terms: D000349:Africa; D000907:Antibodies, Bacterial / Q000097:blood*; D004311:Double-Blind Method; D005260:Female; D018073:Haemophilus Vaccines; D006801:Humans; D007156:Immunologic Memory; D007223:Infant; D008297:Male; D022401:Meningococcal Vaccines / Q000009:adverse effects / Q000276:immunology*; D009345:Neisseria meningitidis / Q000276:immunology*; D011135:Polysaccharides, Bacterial; D013745:Tetanus Toxoid; D018074:Vaccines, Conjugate / Q000009:adverse effects / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines; C055753:Haemophilus influenza type b polysaccharide vaccine-tetanus toxin conjugate; D022401:Meningococcal Vaccines; D011135:Polysaccharides, Bacterial; C000610192:PsACWY vaccine; D013745:Tetanus Toxoid; D018074:Vaccines, Conjugate; C043226:meningococcal group A polysaccharide