LETTERS TO THE EDITOR Response to Hepatitis A Vaccine in Children with Inflammatory Bowel Disease Receiving Infliximab To the Editor: We read with great interest the recent article by Radzikowski et al 1 on immunogenicity of the hepatitis A virus (HAV) vaccine in pediatric patients with inflammatory bowel dis- ease (IBD). As outlined by the authors, there are few studies investigating the immune response to vaccinations in children with IBD. The authors specifi- cally looked at immunogenicity of the HAV vaccine in pediatric IBD patients when compared to healthy controls. They vaccinated eligible patients with Havrix (GlakoSmithKline, Rixensart, Belgium), on a two-dose schedule of 0 and 6–12 months. They measured total anti-HAV antibodies prevaccination, at 4 and 12 weeks after the first dose, and 4 and 12 weeks after the second dose. Among the 66 IBD patients and 68 control patients, they found no sig- nificant difference in seroconversion after the second dose of the vaccine between the two groups (97% vs. 100%, P ¼ 0.2407). 1 6-Mercaptopur- ine (6-MP) or azathioprine (AZA) treatment with and without steroids did not affect seroconversion rates, but monotherapy with steroids reduced the rate of seroconversion at 4 weeks after the second dose. 1 Their results were consistent with existing reports of HAV seroconversion in healthy patients 2 and in patients with chronic liver disease. 3,4 Of note, none of the patients in the study were on a bio- logic medication, such as infliximab. Herein we aimed to investigate the immunogenicity of the HAV vac- cine in pediatric IBD patients receiving infliximab. We screened 100 patients for total anti-HAV antibodies and found that 14 patients (14%) had pro- tective antibodies. We were able to enroll 12 patients who did not have anti-HAV antibodies to receive the full series of the vaccine. We used Havrix on a 0 and 6–12 months schedule, at a dose of 720 enzyme-linked immuno- sorbent assay (ELISA) units (ELU) per 0.5 mL for patients less than 19 years of age and 1440 ELU per 1 mL for patients 19 years of age and older, per the manufacturer’s recommendations. We checked the total anti-HAV pre- vaccination and 4 weeks after the sec- ond dose of the vaccine. The mean age at time of vaccination was 18.3 years (range 13–23 years) with a mean age at IBD diagnosis of 12.8 years. There were eight males and four females in the study. Overall, we found a sero- conversion rate of 92% (11/12 patients) when the total anti-HAV was rechecked 4 weeks after the second dose. All of the patients were receiving infliximab at the time of vaccination and none of the patients were on con- current steroids or 6-MP/AZA. Of note, two of the patients were on con- current methotrexate, both of whom were responders to the HAV vaccine. In summary, we found a high rate of seroconversion to HAV vaccination in pediatric patients treated with inflixi- mab for IBD. Taken together with the results of the study by Radzikowski et al, there is convincing evidence that pediatric IBD patients on a wide variety of medications for control of their disease are likely able to respond adequately to the HAV vaccine. Jonathan Moses, MD Naim Alkhouri, MD Angela Shannon, MD Ariel Feldstein, MD Christine Carter-Kent, MD Department of Pediatric Gastroenterology Cleveland Clinic Cleveland, Ohio REFERENCES 1. Radzikowski A, Banaszkiewicz A, Lazowska- Przeorek I, et al. Immunogenicity of hepatitis A vaccine in pediatric patients with inflamma- tory bowel disease. Inflamm Bowel Dis. 2011; 17:1117–1124. 2. Innis BL, Snitbhan R, Kunasol P, et al. Pro- tection against hepatitis A by an inactivated vaccine. JAMA. 1994;271:1328–1334. 3. Ferreira CT, da Silveira TR, Vieira SM, et al. Im- munogenicity and safety of hepatitis A vaccine in children with chronic liver disease. J Pediatr Gastroenterol Nutr. 2003;37:258–261. 4. Dumot JA, Barnes DS, Younossi Z, et al. Im- munogenicity of hepatitis A vaccine in decom- pensated liver disease. Am J Gastroenterol. 1999;94:1601–1604. Copyright V C 2011 Crohn’s & Colitis Foundation of America, Inc. DOI 10.1002/ibd.21892 Published online 26 September 2011 in Wiley Online Library (wileyonlinelibrary.com). Inflamm Bowel Dis  Volume 17, Number 12, December 2011 E160