Children on immunosuppressive therapy may lose hepatitis B vaccine protection

More than half of children treated with immunosuppressive drugs for gastrointestinal or rheumatological conditions no longer had protective levels of antibodies against hepatitis B virus (HBV) and may require repeat vaccination, according to a study presented at the Pediatric Academic Societies Meeting earlier this month in San Francisco.

Children with inflammatory bowel disease (IBD), juvenile arthritis and other autoimmune conditions are often treated with biologic therapy. While these drugs have transformed management of chronic inflammatory conditions, they can increase the risk of infections, lead to reactivation of chronic viral infections and potentially accelerate the decline of antibody levels in people who have been vaccinated.

HBV reactivation can cause severe hepatitis flares, and the Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices recommends that people starting immunosuppressive therapy be screened for serological markers of hepatitis B immunity and revaccinated if necessary. But this has not been well studied in children.

Emily Smitherman of Cincinnati Children's Hospital and colleagues retrospectively analysed hepatitis B serology results from 315 paediatric gastroenterology and rheumatology patients who received intravenous biologic therapy between October 2015 and June 2016.

The mean age of the children was approximately 17 years. A majority had IBD and used tumour necrosis factor (TNF) inhibitors such as infliximab (Remicade). A third had various rheumatological conditions, mainly juvenile idiopathic arthritis, and were treated with TNF inhibitors or other biologics including anti-IL6, anti-T-cell or anti-B-cell agents.

The researchers found that 66% of the children with IBD and 70% of those with rheumatological conditions tested negative for hepatitis B surface antibody (HBsAb), indicating lack of immunity. There was a trend toward a higher proportion of children lacking immunity in the older age groups; more than 80% of adolescents aged 16 to 20 were no longer immune.

One child had a positive hepatitis B core antibody (HBcAb) test, indicating a prior history of HBV infection and risk for reactivation. None of the children were found to have currently active HBV infection.

Over half of the children who were found to be non-immune were given repeat HBV vaccinations. Among those with complete post-vaccine serology results, 68% tested positive for HBsAb, indicating they had regained protection. This showed that a majority of individuals can still mount an immune response while on biologic therapy.

These study results raise the question of whether all children should be screened for sustained immunity to HBV, not only those receiving immunosuppressive therapy, Smitherman suggested.