Hepatitis B infections in vaccinated Kimberley Aboriginal people
In 2011 the Kimberley Population Health Unit (KPHU) became aware of people in the Kimberley who had been reported to have hepatitis B infection even though they were born at a time which meant they should have been fully vaccinated at birth. This prompted a review of hepatitis B cases in the Kimberley region to see if there was any evidence of vaccine failure occurring.
All cases of hepatitis B infection are notified to the Western Australian Notifiable Infectious Disease Database (WANIDD). These notifications were cross referenced against immunisation records held by KPHU in an electronic database and in paper form. In any cases identified, we looked at maternal serology to see if chronic hepatitis B infection in the mother was the likely reason for infection.
From 1 January 1984 to 31 March 2011, we identified 17 cases of Aboriginal Kimberley residents with hepatitis B infection after vaccination:
- In six cases there was evidence that the mother had chronic infection during pregnancy.
- In seven patients there was no evidence that the mother had chronic infection when they were pregnant, suggesting they became infected in early childhood or through sexual activity and therefore vaccination failure was likely.
- In four cases there was insufficient information to comment on how they became infected.
With the introduction of vaccination the rates of chronic infection are falling, however some children may acquire infection despite vaccination. In this population, infection is more likely to occur during pregnancy and delivery or in childhood than in adulthood.
Prevention and control strategies in the Kimberley therefore should include screening all antenates for hepatitis B infection, follow-up of high risk infants, high rates of vaccination coverage, appropriate opportunistic population screening, monitoring of vaccination status in notified cases and prevention of transmission from those with chronic infection to household contacts.
Emma Griffiths, Carole Reeve, Julia V Marley. Hepatitis B notifications in a vaccinated cohort of Aboriginal people in the Kimberley region. Med J Aust 2014; 201:343-346