title: Antibody persistence for up to 5 years after a fourth dose of Haemophilus influenzae type b and Neisseria meningitidis serogroups C and Y-tetanus toxoid conjugate vaccine (HibMenCY-TT) given at 12-15 months of age.
abstract: BACKGROUND
  A 4-dose series of recently licensed Haemophilus influenzae type b-meningococcal serogroups C and Y-tetanus toxoid conjugate vaccine (HibMenCY-TT) was immunogenic with a clinically acceptable safety profile in infants, with antibodies persisting in most participants for 1 year following dose 4. This study assessed antibody persistence up to 5 years after vaccination.
  
  
  METHODS
  Participants had received HibMenCY-TT or Hib-TT at 2, 4 and 6 months of age. At age 12-15 months, HibMenCY-TT vaccinees received a fourth HibMenCY-TT dose (HibMenCY x 4 group), whereas those who received Hib-TT received a fourth dose of either Hib-TT (Hib) or HibMenCY-TT (HibMenCY x 1). Blood samples were collected 1 month and 1, 3 and 5 years after the last dose for measurement of antipolyribosylribitol phosphate (the Hib capsular polysaccharide) antibodies and serum bactericidal activity (human complement source) against meningococcal serogroups C and Y.
  
  
  RESULTS
  Five years after the fourth dose, the percentages of children with antipolyribosylribitol phosphate ≥0.15 μg/mL in HibMenCY x 4, HibMenCY x 1 and Hib groups were 98.8% (95% confidence interval: 93.5%-100%), 97.3% (85.8%-99.9%) and 92.3% (79.1%-98.4%), respectively. The percentages with human complement serum bactericidal activity ≥1:8 for meningococcal serogroup C were 82.9% (72.5%-90.6%), 73.5% (55.6%-87.1%) and 21.1% (9.6%-37.3%), respectively. The percentages with human complement serum bactericidal activity ≥1:8 for serogroup Y were 69.5% (58.4%-79.2%), 54.3% (36.6%-71.2%) and 18.4% (7.7%-34.3%), respectively.
  
  
  CONCLUSIONS
  HibMenCY-TT given as a 4-dose series or as a single dose at 12-15 months of age induced immune responses for all 3 antigens that lasted for up to 5 years after vaccination in more than half of recipients.
authors: University of Louisville School of Medicine, Louisville, KY 40202, USA. gary.marshall@louisville.edu
authors: Gary S
authors: GS
authors: Marshall
authors: Mark
authors: M
authors: Blatter
authors: Colin
authors: C
authors: Marchant
authors: Emmanuel
authors: E
authors: Aris
authors: Narcisa
authors: N
authors: Mesaros
authors: Jacqueline M
authors: JM
authors: Miller
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D001770:Blood Bactericidal Activity; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D018073:Haemophilus Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D007223:Infant; D008297:Male; D011134:Polysaccharides / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage* / Q000276:immunology*; D013745:Tetanus Toxoid / Q000008:administration & dosage* / Q000276:immunology*; D013997:Time Factors; D014611:Vaccination / Q000379:methods*; D018074:Vaccines, Conjugate
chemical_list: D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines; C527605:Hib-MenCY-TT vaccine; D011134:Polysaccharides; D011135:Polysaccharides, Bacterial; D013745:Tetanus Toxoid; D018074:Vaccines, Conjugate; C008984:polyribitol phosphate