title: Do Dose Numbers Matter?: Evaluation of Differing Infant and Toddler Meningococcal C Conjugate Vaccine Programs in Canadian Children.
abstract: BACKGROUND
  The diversity of Canadian infant meningococcal C conjugate (MenC) vaccine programs is unique among countries providing MenC vaccines and offers a valuable opportunity to determine the optimal vaccine program. This longitudinal study assessed differences in seroprotection by 3 different vaccine schedules in children two years after receiving either 1 toddler MenC vaccine dose (1 dose), 1 infant and 1 toddler dose (2 doses), or 2 infant and 1 toddler MenC vaccine dose (3 doses).
  
  
  METHODS
  Three similar cohorts of healthy infants from 1, 2 and 3 dose program areas were enrolled before to their 12 month toddler dose and vaccinated with MenC-tetanus toxoid (MenC-TT) conjugate vaccine. Sera obtained 2 years later were assayed for serogroup C bactericidal activity using standardized procedures with rabbit as the exogenous complement source. Serum bactericidal activity titers ≥1:8 were considered protective.
  
  
  RESULTS
  Results were available for 384 children. Rates of seroprotection at 36 months of age were significantly different between the 1 and 3 dose programs, but confidence intervals overlapped between the 1 and 2 dose programs and between the 2 and 3 dose programs: 1 dose 92% (95% confidence interval: 86%-96%) versus 99% (95%-100%) with 2 doses and 100% (97%-100%) with 3 doses. Geometric mean titers were significantly different at 12.1 (10.8-13.5), 32.4 (28.9-36.2) and 50.6 (45.7-55.9) in the 1, 2 and 3 dose programs, respectively.
  
  
  CONCLUSIONS
  At 36 months of age, evidence of seroprotection remained for greater than 90% of participants. Our results indicate that 1 toddler dose or 1 infant plus 1 toddler dose with MenC-TT vaccine provides seroprotection against MenC disease in early childhood.
authors.affiliation: From the *Vaccine Evaluation Center, BC Children's Hospital, University of British Columbia, Vancouver, Canada; †Department of Pediatrics and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada; ‡Canadian Center for Vaccinology, IWK Health Centre, Dalhousie University, Halifax, Canada; §Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada; and ¶Institut National de Sante Publique, Quebec City, Canada.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Bettinger
authors.forename: Otto G
authors.initials: OG
authors.lastname: Vanderkooi
authors.forename: David W
authors.initials: DW
authors.lastname: Scheifele
authors.forename: Scott A
authors.initials: SA
authors.lastname: Halperin
authors.forename: James D
authors.initials: JD
authors.lastname: Kellner
authors.forename: Anthony
authors.initials: A
authors.lastname: Schryvers
authors.forename: Gaston
authors.initials: G
authors.lastname: De Serres
authors.forename: Joenel
authors.initials: J
authors.lastname: Alcantara
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood; D002170:Canada; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007114:Immunization / Q000706:statistics & numerical data*; D007115:Immunization Schedule; D007223:Infant; D008297:Male; D022401:Meningococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D022401:Meningococcal Vaccines; C410218:serogroup C meningococcal conjugate vaccine