Fendrix vs Engerix-B for Primo-Vaccination Against Hepatitis B Infection in Patients With Inflammatory Bowel Disease: A Randomized Clinical Trial.

Introduction: To compare Engerix-B and Fendrix hepatitis B virus for primo vaccination in inflammatory bowel disease (IBD).
Methods: Patients with IBD were randomized 1:1 to receive Engerix-B double dose or Fendrix single dose at months 0, 1, 2, and 6. Anti-HBs titers were measured 2 months after the third and fourth doses. Response to vaccination was defined as anti-HBs ≥100 UI/L. Anti-HBs titers were measured 2 months after the third and fourth doses and again at 6 and 12 months after the fourth dose.
Results: A total of 173 patients were randomized (54% received Engerix-B and 46% Fendrix). Overall, 45% of patients responded (anti-HBs ≥100 IU/L) after 3 doses and 71% after the fourth dose. The response rate after the fourth dose was 75% with Fendrix vs 68% with Engerix-B (P = 0.3). Older age and treatment with steroids, immunomodulators, or anti-tumor necrosis factor were associated with a lower probability of response. However, the type of vaccine was not associated with the response. Anti-HBs titer negativization occurred in 13% of patients after 6 months and 20% after 12 months. Anti-HBs ≥100 IU/L after vaccination was the only factor associated with maintaining anti-HBs titers during follow-up.
Discussion: We could not demonstrate a higher response rate of Fendrix (single dose) over Engerix-B (double dose). A 4-dose schedule is more effective than a 3-dose regimen. Older age and treatment with immunomodulators or anti-tumor necrosis factors impaired the success. A high proportion of IBD patients with protective anti-HBs titers after vaccination loose them over time. The risk of losing protective anti-HBs titers is increased in patients achieving anti-HBs <100 IU/L after the vaccination.