title: Effectiveness of pneumococcal conjugate vaccine in infants by maternal influenza vaccination status.
abstract: BACKGROUND
  Influenza virus infection can predispose patients to secondary pneumococcal infections. Children are at greatest risk for pneumococcal infection in the first year of life and are not considered fully protected by pneumococcal conjugate vaccine (PCV) until their third dose at 6 months of age. Infants less than 6 months cannot receive influenza vaccination, though maternal influenza vaccination can protect infants.
  
  
  METHODS
  We conducted a retrospective cohort study of 9807 mother-infant pairs enrolled in a managed care organization for infants born June 1, 2002, to December 31, 2009. Exposure was assessed for receipt of infant PCV only and the combination of PCV and maternal influenza vaccine (trivalent inactivated vaccine). Outcomes of interest were acute otitis media and medically attended acute respiratory infection in the first year of life. We estimated the adjusted incidence of illness, incidence rate ratios and vaccine effectiveness using the ratio of incidence rate ratios between the periods of noncirculating influenza and that of at least local influenza circulation.
  
  
  RESULTS
  For medically attended acute respiratory infection, vaccine effectiveness for the combination of trivalent inactivated vaccine and PCV was 39.6% (95% confidence interval [CI]: 31.6%-46.7%) and for PCV only was 29.8% (95% CI: 11.4%-44.3%). For acute otitis media, vaccine effectiveness for the combination of trivalent inactivated vaccine and PCV was 47.9% (95% CI: 42%-53.3%) and for PCV only was 37.6% (95% CI: 23.1%-49.4%).
  
  
  CONCLUSIONS
  In infants, the combination of maternal influenza vaccine and infant pneumococcal conjugate vaccination confers greater protection from acute otitis media infections and medically attended acute respiratory infections than does PCV alone.
authors.affiliation: From the *Center for Health Research-Southeast, Kaiser Permanente; †Rollins School of Public Health; and ‡Emory Vaccine Center, Emory University, Atlanta GA.
authors.forename: Katharina L
authors.initials: KL
authors.lastname: van Santen
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bednarczyk
authors.forename: Dzifa
authors.initials: D
authors.lastname: Adjaye-Gbewonyo
authors.forename: Walter A
authors.initials: WA
authors.lastname: Orenstein
authors.forename: Robert
authors.initials: R
authors.lastname: Davis
authors.forename: Saad B
authors.initials: SB
authors.lastname: Omer
mesh_terms: D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control; D008137:Longitudinal Studies; D009035:Mothers / Q000706:statistics & numerical data*; D010033:Otitis Media / Q000453:epidemiology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000517:prevention & control; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D014611:Vaccination / Q000706:statistics & numerical data; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
chemical_list: D007252:Influenza Vaccines; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate