Infliximab IBD Influenza Vaccine Study

Effect of Influenza Vaccination Timing on Immune Response in Patients With Inflammatory Bowel Disease on Infliximab Therapy: A Randomized Equivalence Trial

The investigators will compare the immunogenicity of influenza vaccine in adults and children with inflammatory bowel disease by timing of vaccine in relation to maintenance infliximab dosing. The primary objective is to compare the proportion of IBD patients on maintenance infliximab who mount serologic protection to each component of the influenza vaccination between patients vaccinated on day of infliximab infusion (Day 0 to 4) and patients vaccinated at the mid-point between infliximab infusions (Day 21 to 28). Serologic protection will be defined by a hemagglutination-inhibition titer ≥ 1:40. The secondary objective is to compare the proportion of IBD patients who mount an immunogenic response (≥ 4-fold increase from pre to post-vaccination titer) to each component of the influenza vaccination between patients vaccinated on day of infliximab infusion and those vaccinated at the mid-point.

To compare the proportion of IBD patients on maintenance infliximab who mount serologic protection to each component of the influenza vaccination between patients vaccinated on day of infliximab infusion (Day 0 to 4) and patients vaccinated at the mid-point between infliximab infusions (Day 21 to 28). Serologic protection will be defined by a hemagglutination-inhibition titer ≥ 1:40.

To compare the proportion of IBD patients on maintenance infliximab who mount an immunogenic response to each component of the influenza vaccination between patients vaccinated on day of infliximab infusion (Day 0 to 4) and patients vaccinated at the mid-point between infliximab infusions (Day 21 to 28). Immunogenicity will be defined as a fourfold or greater differences in titer between pre and post-vaccination sera.

To evaluate the number of participants with early serious adverse reactions (≤ 3 days post-vaccination)

To evaluate the change in disease activity score from baseline using the validated instruments of the Pediatric Ulcerative Colitis Activity Index for participants with Ulcerative Coltiis and the Harvey Bradshaw Index for participants with Crohn's Disease

Inclusion Criteria: Diagnosis of IBD established by accepted criteria On maintenance infliximab administered every 6 to 8 weeks (already received at least 6 weeks of infliximab) Between ages 9 and 60 years Exclusion Criteria: Pregnancy Hypersensitivity reaction to previous dose of influenza vaccine Known hypersensitivity to eggs or chicken or other components of influenza vaccine