Hepatitis B notifications in a vaccinated cohort of Aboriginal people in the Kimberley region.

Objectives: To identify cases of hepatitis B infection after vaccination in
Kimberley residents and determine maternal serostatus as a potential indicator
of mode of transmission.
Design and participants: Retrospective review of Kimberley residents with
notifi ed hepatitis B infection using records of vaccination history and child and
maternal serology.
Main outcome measures: Confi rmed cases of hepatitis B infection after
vaccination; chronic infection in cases of hepatitis B infection after vaccination;
maternal serostatus in confi rmed cases of hepatitis B infection after vaccination.
Results: From 1 January 1984 to 31 March 2011, we identifi ed 17 cases of
Aboriginal residents with hepatitis B infection after vaccination (10 chronic
infections, fi ve not defi ned and two cleared). In six patients, maternal chronic
infection had been identifi ed at some stage, raising the possibility of vertical
transmission. In seven patients, maternal serology or evidence of subsequent
acquisition suggested that horizontal transmission and therefore vaccination
failure was likely. For four patients, there was inadequate information to assess
possible mode of transmission.
Conclusions: Hepatitis B infection after full vaccination is not limited to
children of mothers with active infection. Further undiagnosed infections in the
Kimberley are likely, and active monitoring to detect the extent and likely cause
of hepatitis B infection in vaccinated children is needed. In children where vertical
transmission is a risk, prospective follow-up is warranted.