title: Sex-dependent immune responses to infant vaccination: an individual participant data meta-analysis of antibody and memory B cells.
abstract: BACKGROUND
  Biological sex can be an important source of variation in infection and immunity and sex-dependent differences in immune response to vaccination have been reported in some studies.
  
  
  METHODS
  We conducted an individual participant data meta-analysis of vaccine trials from one research centre, in which vaccines were administered to children under three years of age and immunological parameters measured. Log-transformed antigen-specific antibody and memory B cell results were meta-analysed and differences between girls and boys reported as geometric mean ratios.
  
  
  RESULTS
  Antibody and memory B cell data were available from nine trials and 2378 children. Statistically significant differences between girls and boys were observed for diphtheria toxoid, capsular group A, W, and Y meningococcal, and pneumococcal vaccines. No sex-differences were observed for responses to Haemophilus influenzae type b, capsular group C meningococcal or tetanus toxoid vaccines.
  
  
  CONCLUSIONS
  In young children, immune responses to vaccines were consistently higher or equivalent in girls compared with boys. In no instance were responses in boys significantly higher than girls. While these data do not indicate differences in protection conferred by immunisation in boys and girls, they do support further consideration of biological sex in planning of clinical trials of vaccines.
authors.affiliation: Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK; Oxford Vaccine Group, Department of Paediatrics, University of Oxford, UK. Electronic address: merryn.voysey@phc.ox.ac.uk.
authors.forename: Merryn
authors.initials: M
authors.lastname: Voysey
authors.affiliation: Paediatric Infectious Diseases Research Group, Institute for Infection and Immunity, St George's University of London, UK; Oxford Vaccine Group, Department of Paediatrics, University of Oxford, UK; Oxford University Clinical Academic Graduate School, Medical Sciences Division, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors.forename: Charlotte I S
authors.initials: CI
authors.lastname: Barker
authors.affiliation: Oxford Vaccine Group, Department of Paediatrics, University of Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Snape
authors.affiliation: Oxford Vaccine Group, Department of Paediatrics, University of Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK.
authors.forename: Dominic F
authors.initials: DF
authors.lastname: Kelly
authors.affiliation: Oxford Vaccine Group, Department of Paediatrics, University of Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK.
authors.forename: Johannes
authors.initials: J
authors.lastname: Trück
authors.affiliation: Oxford Vaccine Group, Department of Paediatrics, University of Oxford, UK; NIHR Oxford Biomedical Research Centre, Oxford, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pollard
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D006801:Humans; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007156:Immunologic Memory; D007223:Infant; D008297:Male; D016032:Randomized Controlled Trials as Topic; D012737:Sex Factors; D014611:Vaccination; D014612:Vaccines / Q000008:administration & dosage
chemical_list: D014612:Vaccines
keywords: Antibody; Individual participant data; Infant; Memory B cells; Meta-analysis; Sex-differences; Vaccine