Introduction: Neonates exposed to tumour necrosis factor [TNF] alpha inhibitors in utero are born with detectable drug levels which can still be detected throughout the first year of life. Since 2011, the hepatitis B virus [HBV] vaccine is routinely administered to all newborns in the Netherlands. Adults treated with anti-TNF have been reported to respond inadequately to the HBV vaccine. The aim of this study was to compare anti-HB levels in anti-TNF-exposed children with non-exposed children following routine Dutch HBV vaccination. Methods: We performed a cross-sectional, controlled cohort study from 2014 to 2017 in a single, tertiary referral centre. Pregnant women treated with anti-TNF for inflammatory bowel disease [IBD] and their subsequent children were recruited from the IBD preconception outpatient clinic. Pregnant women not treated with anti-TNF for IBD and their subsequent children were eligible as controls. Adherence to the Dutch National Vaccination Programme was mandatory for participation in this study. A venous blood sample was obtained 1 month after final HBV vaccination. Anti-HB levels were measured by enzyme-linked immunosorbent assay. Results: Anti-HB levels at 12 months did not differ between the anti-TNF-exposed [n = 15] and the control group [n = 12] [< 1000 IU/l vs < 1000 IU/l, p = 0.59]. All children were successfully immunized against HBV, defined as anti-HB < 10 IU/l. Median anti-TNF levels determined in cord blood at birth were 9.0 µg/ml [interquartile range: 3.0–15.0 µg/ml] for infliximab and 0.4. µg/ml [interquartile range: 0.3–0.6 µg/ml] for adalimumab. There were no differences in general birth and health outcomes. Conclusion: Children born with detectable anti-TNF levels can be effectively vaccinated against HBV.

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Journal of Crohn's and Colitis
Department of Pediatrics

de Lima, A, Kanis, S.L, Escher, J.C, & van der Woude, C.J. (2018). Hepatitis b vaccination effective in children exposed to anti-Tumour necrosis factor alpha in utero. Journal of Crohn's and Colitis, 12(8), 948–953. doi:10.1093/ecco-jcc/jjy053