Session Title: VACCINE AND PREVENTION
MARKERS OF HBV INFECTION IN 10-12-YEAR OLD CHILDREN VACCINATED AGAINST HEPATITIS B IN INFANCY
M. Pokorska-Lis1,2, M. Marczynska1,2
1Department of Children's Infectious Diseases, Medical University of Warsaw, 2Regional Hospital of Infectious Diseases, Warszawa, Poland
Background: Vaccination is the best method of protection against hepatitis B (HB). The efficacy of immunization is high, estimated at about 95% in healthy population. However, the duration of protection remains unknown.
Aim: The aim of the study was to determine the direct efficacy of HB vaccine in 10-12-year old children immunized in infancy.
Material and methods: In 121 children aged 10-12 ys. immunized against HB with recombinant vaccine in infancy (with 4-dose schedule, first dose given at birth, 10 µg) markers of HBV infection: HB surface antigen (HBsAg - marker of chronic hepatitis) and antibodies to HB core antigen (anti-HBc total - marker of past HBV infection) as well as anti-HBs antibodies (as a marker of seroprotection against HB) were determined. Titers of anti-HBs ≥ 10 IU/l were defined as protective.
Results: Of the 121 participants, 97 (80%) had protective levels of anti-HBs. None were HBsAg positive nor had history of hepatitis. In 4 children (3,3%), despite protective titers of anti-HBs (54 to ≥ 1000 IU/l), anti-HBc were positive. Amongst anti-HBc positive children everyone had risk factors of HBV infection in anamnesis (hospitalization, surgery, HBV-infected parents). In one child, in which HBV DNA using PCR method was additionally determined, it was negative. In other three HBV DNA is to be examined.
Conclusions: Vaccination is highly effective in preventing chronic HB for 10 to 12 years after infant vaccination. However, a number of children becomes HBV infected, which needs to be considered due to the risk of occult hepatitis.