Hepatitis B Immunity in Children on Immunomodulators: Implications From a Pediatric Dermatology Cohort and Review of the Literature.

BACKGROUND/OBJECTIVES: This study aims to determine the level of hepatitis B virus (HBV) immunity in patients who had HBV serologic testing prior to starting immunomodulatory medication for dermatologic conditions at a single institution and to review evidence on waning immunity, serologic interpretation, and revaccination. METHODS: We performed a retrospective chart review of pediatric and young adult patients initiated on immunomodulatory therapy for dermatologic conditions who had HBV serologic testing prior to initiation. A focused literature review was conducted on durability of HBV immunity, HBV serologies in the context of immunomodulatory medications, and revaccination recommendations. RESULTS: In this cohort of 23 children, roughly 40% lacked HBV serologic immunity. Prior studies demonstrated that antibody-mediated protection is heterogeneous and anti-HBs titers decline over time. Existing guidelines are largely derived from adult populations. Evidence regarding revaccination strategies is mixed. Notably, absence of detectable anti-HBs antibodies does not always equate to loss of immune memory or susceptibility to infection. CONCLUSIONS: Anti-HBs titers are variable and wane over time. Experts agree that patients should receive all recommended vaccinations before starting immunomodulatory therapy and be screened for HBV beforehand, based on adult guidelines. It is uncertain how well these recommendations apply to children, who generally have lower HBV risk and prevalence. Guidance is needed on how to manage pediatric patients without serologic evidence of HBV immunity before beginning biologic treatments.