title: Immune response to influenza vaccine in pediatric patients with inflammatory bowel disease.
abstract: OBJECTIVE
  The aim of this study was to compare response to inactivated influenza vaccine in healthy children and pediatric patients with inflammatory bowel disease (IBD).
  
  
  METHODS
  A prospective, open-label, controlled clinical trial during influenza seasons of 2002-2004 was performed. Single-dose inactive trivalent influenza vaccine was administered. Immune response to vaccination was measured by pre-immunization and postimmunization hemagglutinin inhibition titers. A postimmunization hemagglutinin inhibition titer of 40 or higher was considered protective against influenza. IBD activity and adverse events were recorded.
  
  
  RESULTS
  Eighty subjects were enrolled (29 healthy controls, 51 IBD patients). One patient did not complete the study. Patients were divided into 3 subgroups: infliximab and immunomodulatory (16), immunomodulatory (20), and anti-inflammatory therapy (14). Immunomodulatory therapy included corticosteroids, 6-mercaptopurine, or methotrexate. Overall, there was a statistically significant decrease in immune response in patients compared with healthy controls who received 1 influenza vaccine antigen (B/Hong Kong, P = .0125). Patients receiving infliximab and immunomodulatory therapy were less likely to respond to 2 influenza vaccine antigens (A/New Caledonia/20/99 and B/Hong Kong/330/2001, P = .018 and .0002, respectively). Fifteen subjects (19%) reported 19 mild adverse events: 11 (14%) reported soreness at the site, 4 (5%) reported having a cold, 3 (4%) reported flu-like symptoms, and 1 (1%) reported a headache. The clinical activity of IBD was not affected by vaccination.
  
  
  CONCLUSIONS
  The serologic conversion rate to influenza vaccine in patients with IBD ranged from 33% to 85%. Patients on concomitant infliximab and immunomodulatory therapy are at risk of inadequate response to vaccination. The vaccine was safe and did not affect IBD activity.
authors.affiliation: Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Petar
authors.initials: P
authors.lastname: Mamula
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Markowitz
authors.forename: David A
authors.initials: DA
authors.lastname: Piccoli
authors.forename: Alexander
authors.initials: A
authors.lastname: Klimov
authors.forename: Louis
authors.initials: L
authors.lastname: Cohen
authors.forename: Robert N
authors.initials: RN
authors.lastname: Baldassano
mesh_terms: D000293:Adolescent; D002648:Child; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D006388:Hemagglutinins / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000188:drug therapy / Q000276:immunology*; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D008297:Male; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D006388:Hemagglutinins; D007166:Immunosuppressive Agents; D007252:Influenza Vaccines