The introduction of vaccinations against viral hepatitis B in the years 1994-1996 in Poland significantly improved the epidemiological situation of hepatitis B virus (HBV) infections in our country. According to the report of the National Institute of Public Health - National Institute of Hygiene in 2018, 40 cases of acute hepatitis B were noted while still in the 1980s between 10 and 20 thousand new cases were reported annually. The aim of the study was to determine whether in children treated with biological drugs (adalimumab, etanercept, infliximab) due to juvenile idiopathic arthritis (JIA), vaccinated against hepatitis B in infancy, a protective concentration of anti-HBs antibodies persists. In patients, the value ≥ 10 mIU/ml is regarded as a protective concentration of antibodies, determined at least four weeks after administration of the last vaccine dose. Among healthy individuals, presence of anti-HBs antibodies in any concentration means seroprotection. No booster vaccinations are recommended in basically vaccinated healthy individuals.
The concentrations of anti-HBs antibodies were determined in 56 children with JIA (38 girls - 67.9% and 18 boys - 32.1%) aged from 2 years and 4 months to 17.5 years, treated for at least three months with biological drugs. The diagnosis of JIA was made based on the International League of Associations for Rheumatology (ILAR) criteria. All studied patients were at the stable stage of the disease and received a full course of hepatitis B vaccination during infancy (in accordance with 0,1,6 months injection scheme).
In the studied children a protective anti-HBs antibody concentration was found in 34 cases (60.7%), and 22 children (39.3%) had anti-HBs antibody concentration < 10 mIU/ml (in these children no seroprotection was found).
The post-vaccination antibody concentration should be determined in children with JIA, treated with biological drugs and, in case of absence of a protective concentration, revaccination should be started.