Effectiveness of universal hepatitis A immunization of children in Minsk City, Belarus: four‐year follow‐up

Abstract

Hepatitis A is a reportable disease in Belarus. Universal hepatitis A vaccination of children aged 6 years in Minsk City began in 2003. This analysis was conducted to evaluate the short-term impact of the program. Hepatitis A incidence data from 1954 to 2006 was compiled. Vaccination effectiveness was estimated by comparing the incidence of reported hepatitis A cases after 4 years of immunization (2006) with the incidence when the vaccination program started (2003). The vaccines used were Avaxim 160 or Avaxim 80 (95%) and Havrix 720 (5%). From 2003 through 2006, hepatitis A incidence in vaccinated children under 14 years was 20-fold lower than the incidence in unvaccinated children (0.3 cases/10000 vs 5.98/10000; odds ratio = 0.05, 95% CI: 0.012-0.202), for a vaccination effectiveness of 95%. The decreased incidence of hepatitis A in all age groups in 2006 (by 12 times in preschool children aged 1-5 years, 13 times in children aged 10-14 years and 4-6 times among adults), including those without high coverage by vaccination, suggest a herd effect. Routine vaccination also resulted in a shift of the age pattern of hepatitis A morbidity. The proportion of cases in children under 14 years decreased from 33% to 41% in 2000-2002 to 7% in 2005-2006. We conclude that introduction of universal hepatitis A vaccination in Minsk resulted in sharply reduced incidence in both vaccinated and unvaccinated children. Hepatitis A virus circulation might decrease further by beginning vaccination at a younger age.