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Kawerau revisited: hepatitis A and B seroprevalence in 1984 and 1993
Aims:
To determine if protection against hepatitis B is maintained in a cohort of children nine years after primary vaccination; To compare the prevalence of hepatitis B infection in 1984, before the introduction of hepatitis B vaccine, with that in 1993; To compare the prevalence of hepatitis A antibody (anti-HAV) in children in 1984 and 1993.
Methods:
Serum samples collected from children attending Kawerau Intermediate School in 1993 were tested for hepatitis B markers and anti-HAV, and the results were compared with those in children attending the same school in 1984.
Results:
Antibody to hepatitis B surface antigen (anti-HBs) was detected in 91.8% of children documented to have received hepatitis B vaccine in 1984. Seroconversion for antibody to hepatitis B core antigen (anti-HBc) had occurred in 5%. None had suffered a clinical illness. No vaccinee had a positive test for hepatitis B surface antigen (HBsAg). The prevalence of hepatitis B infection had fallen from 71.7% in 1984 to 24.2% in 1993. The prevalence of hepatitis A was 29.6% in 1984 and 0.4% in 1993.
Conclusions:
Protection against clinical disease and chronic hepatitis B infection is maintained nine years after primary vaccination. Hepatitis A has virtually disappeared among children in Kawerau.