title: Understanding reduced rotavirus vaccine efficacy in low socio-economic settings.
abstract: BACKGROUND
  Rotavirus vaccine efficacy ranges from >90% in high socio-economic settings (SES) to 50% in low SES. With the imminent introduction of rotavirus vaccine in low SES countries, understanding reasons for reduced efficacy in these settings could identify strategies to improve vaccine performance.
  
  
  METHODS
  We developed a mathematical model to predict rotavirus vaccine efficacy in high, middle and low SES based on data specific for each setting on incidence, protection conferred by natural infection and immune response to vaccination. We then examined factors affecting efficacy.
  
  
  RESULTS
  Vaccination was predicted to prevent 93%, 86% and 51% of severe rotavirus gastroenteritis in high, middle and low SES, respectively. Also predicted was that vaccines are most effective against severe disease and efficacy declines with age in low but not high SES. Reduced immunogenicity of vaccination and reduced protection conferred by natural infection are the main factors that compromise efficacy in low SES.
  
  
  CONCLUSIONS
  The continued risk of severe disease in non-primary natural infections in low SES is a key factor underpinning reduced efficacy of rotavirus vaccines. Predicted efficacy was remarkably consistent with observed clinical trial results from different SES, validating the model. The phenomenon of reduced vaccine efficacy can be predicted by intrinsic immunological and epidemiological factors of low SES populations. Modifying aspects of the vaccine (e.g. improving immunogenicity in low SES) and vaccination program (e.g. additional doses) may bring improvements.
authors.affiliation: National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Lopman
authors.forename: Virginia E
authors.initials: VE
authors.lastname: Pitzer
authors.forename: Rajiv
authors.initials: R
authors.lastname: Sarkar
authors.forename: Beryl
authors.initials: B
authors.lastname: Gladstone
authors.forename: Manish
authors.initials: M
authors.lastname: Patel
authors.forename: John
authors.initials: J
authors.lastname: Glasser
authors.forename: Manoj
authors.initials: M
authors.lastname: Gambhir
authors.forename: Christina
authors.initials: C
authors.lastname: Atchison
authors.forename: Bryan T
authors.initials: BT
authors.lastname: Grenfell
authors.forename: W John
authors.initials: WJ
authors.lastname: Edmunds
authors.forename: Gagandeep
authors.initials: G
authors.lastname: Kang
authors.forename: Umesh D
authors.initials: UD
authors.lastname: Parashar
mesh_terms: D017677:Age Distribution; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D005759:Gastroenteritis / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D007223:Infant; D007231:Infant, Newborn; D008800:Mexico / Q000453:epidemiology; D008954:Models, Biological; D012400:Rotavirus Infections / Q000191:economics* / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control*; D022243:Rotavirus Vaccines / Q000191:economics* / Q000276:immunology*; D012959:Socioeconomic Factors; D016896:Treatment Outcome
chemical_list: D022243:Rotavirus Vaccines