Hepatitis A disease following the implementation of universal vaccination: Who is at risk?

Summary.  The incidence of acute hepatitis A in Israel has decreased 25 folds in less than a decade, following the introduction of a two-dose universal toddler’s hepatitis A immunization in July 1999. This retrospective study describes demographic data and behavioural determinants of hepatitis A patients following the implementation of a vaccination programme. All records of hepatitis A patients reported to the Ministry of Health during the years 2003 through 2005 were reviewed, and an epidemiological investigation was conducted. During the study period, 420 hepatitis A patients were reported, representing an average annual incidence of two per 100 000 population. Case fatality rate was 0.5%. The majority of the patients were younger than 15 years of age, males and non-Jewish. The highest incidence was recorded in east Jerusalem, where vaccine coverage is relatively low. After exclusion of 165 east Jerusalem patients, 133 (52.2%) patients were available for an interview. Of those, 16 (6%) had possible occupational exposure, 37 (27.8%) travelled to endemic areas, 44 (17%) were contacts of hepatitis A cases, and 3 male patients had sex with men. No known risk determinant was identified in 33 (24.8%) patients. Four patients (3%) were previously immunized with one dose, and none had two doses. The introduction of universal toddler hepatitis A vaccination decreased morbidity. Most of the patients who were detected 4–6 years after the implementation of the vaccination programme could be classified into one of the known risk groups for hepatitis A infection or living in a partly vaccinated community.