A survey of adults with IBD conducted by Melmed et al. and published in 2006 demonstrated that only 28 % received annual influenza immunizations, and that very few patients have been immunized against pneumococcus [9]. A comparable pediatric study by Crawford et al. demonstrated that only 5 % of children had been appropriately immunized against pneumococcus, and fewer than 20 % of Australian children had been immunized against influenza [10]. The reasons for this reluctance to undergo recommended immunization include concerns that the vaccine will be ineffective, concerns that they will experience an adverse effect of the vaccine, and concerns that the vaccine may cause a flare of their disease. These concerns have recently been addressed by several pediatric studies that demonstrate inactivated vaccines are generally safe and effective in children with IBD.

The best studied vaccine in children with IBD is the trivalent influenza vaccine, which is both safe and immunogenic in children and young adults. This vaccine is usually administered in the fall and protects against three strains of influenza. For the last several years, the vaccine has generated protection against two strains of influenza A and one strain of influenza B. Three prospective studies have demonstrated that the trivalent influenza vaccine is usually well tolerated in children with IBD, including those receiving immunosuppressive therapy. However, immunogenicity may be reduced, especially in patients receiving biologic therapy. Mamula et al. performed a prospective study using the 2002–2004 vaccine, in which 51 children with IBD and 29 healthy children were immunized. Compared to the healthy controls, children with IBD receiving combination therapy (with immunomodulators and biologics) were less likely to respond to two of the three strains in the influenza vaccine [11]. In contrast, Lu et al. demonstrated a good response to the 2007–2008 influenza vaccine and a high prevalence of seroprotection to both of the influenza A strains in the vaccine. The less immunogenic influenza B strain, however, resulted in a decreased rate of seroprotection in patients receiving anti-TNF therapy [12]. The most recent study by deBruyn et al. again demonstrated excellent safety and good response to the two A strains in the vaccine, but decreased immune response to the B strain [13]. None of these studies demonstrated any increase in adverse events or increase in IBD flares. In summary, data from influenza vaccine studies in pediatric IBD support the recommendation that children with IBD receive annual influenza immunizations. Even patients on immunosuppressive therapies respond well to the two A strains in the vaccine, though antibody titers to the B strain may be reduced.

Hepatitis B boosters have also been studied in children with IBD. Patients with latent hepatitis B who are treated with antitumor necrosis factor inhibitors are at risk for viral reactivation leading to severe viral hepatitis or even liver failure. Moses et al. conducted a prospective study of hepatitis B status in their IBD population, and documented that 13 % had never been immunized against hepatitis B, and that approximately half of patients did not have protective levels of anti-HBs. The investigators then immunized 34 of the patients without protective titers and noted a 76 % response rate. Children and young adults receiving infliximab more frequently (approximately every 5 weeks) were less likely to respond to the booster dose of hepatitis B [14].