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Background: 4CMenB is immunogenic in infants and toddlers. We assessed persistence of human complement serum bactericidal activity (hSBA) following a fourth dose administered at 12, 18 or 24months and characterised the antibody response to a fifth dose administered at 4years of age., Methods: A phase 3, open label, multi-centre extension to a randomised controlled trial conducted in four countries (number of centres): Czech Republic (nineteen), Italy (four), Spain (four) and the United Kingdom (four). Four-year-old children who were either 4CMenB-naïve or had previously received a variety of 3-dose infant priming schedules and a booster vaccine as toddlers (follow-on group) were recruited. Venous blood samples were obtained to determine hSBA against four reference strains; acting as targets to assess immunity to each of the vaccine antigens, NadA (5/99), fHbp (H44/76), PorA (NZ98/254), and NHBA (M10713) at baseline (prior to vaccination, all participants) and one month following a dose of 4CMenB for all vaccine-naïve and follow-on participants primed with the 2, 3, 4 schedule, and a third of follow-on participants primed with a 2, 4, 6month schedule., Results: At baseline (prior to vaccination), the proportion of participants (n=468) with hSBA titers⩾5 was similar across all followon groups: 89-100% against 5/99; 12-35% for H44/76; 8-12% for NZ98/254 and 53-80% for M10713 compared with 5%, 0%, 0%; and 60% respectively, for the vaccine-naïve controls (n=206). Following a dose of 4CMenB at 4years of age, this increased to 100% (5/99), 97-100% (H44/76), 80-95 % (NZ98/254) and 84-100% (M10713) (n=210), compared with 89%, 70%, 24%, and 76% respectively for vaccine-naïve controls (n=192)., Conclusion: Waning of protective antibodies occurred 24–36 months after toddler booster regardless of age at boost. This was least marked against target strains 5/99 and M10713. A robust memory response occurred after a booster dose given at 4 years of age., (Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: The use of different limbs for the administration of sequential doses of an intradermal rabies vaccine was shown to result in reduced vaccine immunogenicity. We aimed to assess whether this phenomenon also occurs with routine infant vaccines., Methods: In this open-label, randomised, controlled study, eligible healthy infants 6-12 weeks of age recruited through five clinical trials units (four in the UK and one in Malta) were randomly assigned in a 1:1 ratio to two vaccination groups: consistent limb or alternating limb. Infants in the consistent limb group received the diphtheria-tetanus-acellular pertussis-inactived polio-Haemophilus influenzae type b combined vaccine (DTaP-IPV-Hib) at 2, 3, and 4 months of age, and the pneumococcal conjugate vaccine (PCV13) at 2, 4, and 12 months, all administered to the right leg. Infants in the alternating limb group received DTaP-IPV-Hib in the left leg at 2 months and in the right leg at 3 and 4 months; and PCV13 in the left leg at 2 months, in the right leg at 4 months, and in the left arm at 12 months. All infants in both groups received the combined H influenzae type b and capsular group C Neisseria meningitidis tetanus toxoid conjugate vaccine (Hib-MenC-TT), administered in the left leg at 12 months. Randomisation was achieved by randomly generated codes, with permuted block size of 30, and was stratified by study site. Group allocation was not masked from study staff and parents of participants after enrolment, but group allocation was masked from laboratory staff assessing blood samples. The current study was a prespecified secondary objective of a parent phase 4 trial that assessed the induction of immunity following varying schedules of vaccination with glyco-conjugate capsular group C Neisseria meningitidis (Men C) vaccines in infancy. The objective of the current study was to compare the immunogenicity and reactogenicity of vaccines delivered in either consistent or alternating limbs. Immunogenicity was assessed by comparing serum IgG geometric mean concentrations at 5, 12, 13, and 24 months, analysed per protocol. This study is registered with ClinicalTrials.gov, number NCT01129518., Findings: Between July 5, 2010, and Aug 1, 2013, we enrolled 509 infants and randomly allocated them to the consistent limb group (n=254) or the alternating limb group (n=255). Anti-H influenzae type b anti-polyribosylribitol phosphate IgG geometric mean concentrations were lower in the consistent limb group than in the alternating limb group at 5 months (consistent limb 0·41 μg/mL [95% CI 0·31-0·54] vs alternating limb 0·61 μg/mL [0·45-0·82]; p=0·0268) and at 12 months (0·35 μg/mL [0·28-0·43] vs 0·50 μg/mL [0·40-0·62]; p=0·0136). Anti-tetanus toxoid antibody IgG geometric mean concentrations were lower in the consistent limb group (1·63 IU/mL [95% CI 1·40-1·90]) than in the alternating limb group (2·30 IU/mL [1·97-2·68]) at 13 months (p=0·0008) and at 24 months (0·44 IU/mL [0·37-0·52] vs 0·61 IU/mL [0·51-0·73]; p=0·0074). Anti-pneumococcal IgG geometric mean concentrations were similar between both groups at all timepoints. The proportions of participants who had adverse events did not differ between the two groups., Interpretation: Use of different (alternating) limbs for sequential doses of routine infant vaccines does not reduce, and might enhance, immunogenicity. The underlying mechanism for this finding warrants further research., Funding: NIHR Oxford Biomedical Research Centre and GlaxoSmithKline Biologicals., (Copyright © 2015 Elsevier Ltd. All rights reserved.)