Immunogenicity and safety of the inactivated hepatitis A vaccine in children with juvenile idiopathic arthritis on methotrexate treatment: a matched case-control study.

OBJECTIVES: To describe the immunogenicity and side effects of immunisation against hepatitis A virus (HAV) in JIA patients on methotrexate treatment, who have not been previously exposed to HAV.

METHODS: Case-control study performed in JIA patients and healthy controls matched on age and gender. The subjects received two doses of inactivated anti-HAV vaccine (720 mIU/ml) intramuscularly at 0 and 6 months. Seroconversion, seroprotection rates and anti-HAV-IgG titres were measured at 1, 7 and 18 months. Children were monitored for adverse events.

RESULTS: 83 JIA patients and 76 controls were enrolled in the study. At one month, seroprotection rates were lower in children with, as compared to those without JIA (48.2% vs. 65%; p=0.05). At 7 and 18 months, rates of seroprotection rose significantly and were similar in both groups. The titre of anti-HAV-IgG was lower in children with JIA than healthy children at all time points (p<0.001). Vaccines were well tolerated.

CONCLUSIONS: Two doses of inactivated HAV vaccine were well tolerated and immunogenic in most immunosuppressed children with JIA; however, a single dose of HAV vaccine was insufficient to induce seroprotection in half of the patients. Further studies are required to analyse the long-term immunity against HAV in this population and optimal HAV immunisation regimen.