Immunogenicity and safety of influenza vaccination in children with inflammatory bowel disease.

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.