title: Immunogenicity and safety of influenza vaccination in children with inflammatory bowel disease.
abstract: BACKGROUND
  Protection against vaccine-preventable diseases is important in inflammatory bowel disease (IBD) because of increased susceptibility and severity of infection with immunosuppressive therapy. However, immunosuppressive therapy may affect vaccine response. This study aimed to evaluate immunogenicity and safety of influenza vaccination in children with IBD.
  
  
  METHODS
  In this prospective cohort study, 60 children with IBD and 53 healthy controls had serum collected for preimmunization hemagglutination-inhibition antibody titers to the 2008 inactivated influenza vaccine components. Three to 5 weeks following vaccine [A/Brisbane/10/2007(H3N2), A/Brisbane/59/2007(H1N1), B/Florida/4/2006] administration, all participants had serum collected for postimmunization titers. A 4-fold or greater increase between pre- and postimmunization titers indicated an immunogenic response; a postimmunization titer ≥1:40 indicated serologic protection. Children with IBD were classified into immunosuppression status by therapy.
  
  
  RESULTS
  Seventy percent, 72%, and 53% of children with IBD mounted an immunogenic response to H3N2, H1N1, and influenza B components, respectively. Among children with IBD, serologic protection was achieved in 95%, 98%, and 85% to H3N2, H1N1, and influenza B components, respectively. For influenza B, children with IBD were less likely to mount an immunogenic response compared to controls (53% versus 81%, P = 0.0009), and immunosuppressed children with IBD were less likely to achieve serologic protection compared to nonimmunosuppressed children with IBD (79% versus 100%, P = 0.02). The majority (98%) tolerated the vaccine.
  
  
  CONCLUSIONS
  Although children with IBD achieve appropriate immunogenicity to influenza A, immunogenicity to influenza B appears to be diminished, especially with immunosuppressive therapy.
authors.affiliation: Division of Paediatric Gastroenterology and Nutrition, Department of Paediatrics, Alberta Children's Hospital, Faculty of Medicine, University of Calgary, Canada. jennifer.debruyn@albertahealthservices.ca
authors.forename: Jennifer C C
authors.initials: JC
authors.lastname: deBruyn
authors.forename: Robert
authors.initials: R
authors.lastname: Hilsden
authors.forename: Kevin
authors.initials: K
authors.lastname: Fonseca
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Russell
authors.forename: Gilaad G
authors.initials: GG
authors.lastname: Kaplan
authors.forename: Otto
authors.initials: O
authors.lastname: Vanderkooi
authors.forename: Iwona
authors.initials: I
authors.lastname: Wrobel
mesh_terms: D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D005260:Female; D005431:Florida; D005500:Follow-Up Studies; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D015212:Inflammatory Bowel Diseases / Q000276:immunology* / Q000517:prevention & control*; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology*; D009981:Influenza B virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000276:immunology*; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D015996:Survival Rate; D013997:Time Factors; D014611:Vaccination
chemical_list: D000914:Antibodies, Viral; D007166:Immunosuppressive Agents; D007252:Influenza Vaccines