Geographic representativeness for sentinel influenza surveillance: implications for routine surveillance and pandemic...

To review the guidelines for geographic representativeness applied to sentinel influenza surveillance as proposed in the Framework for an Australian Influenza Pandemic Plan (1999).

The number of sentinel practices, participating general practitioners and their consultation rates per 100,000 population, by region, were described for the Victorian sentinel surveillance system for 2003 and 2004. Influenza-like illness rates per 1,000 consultations were calculated for all participating practices and for a subset of regular participators. Indicators of seasonal influenza activity, set according to predefined thresholds, were compared in the two groups.

During these two influenza seasons, a subset of approximately one-quarter (27%) of participating practices provided almost half (45%) of the patient swabs and detected the same level of influenza activity over two influenza seasons as all participating practices. However, this subset of GPs recorded only 0.3% of all GP consultations in Victoria in 2004.

There should be an updated, evidence-based strategy for interpandemic influenza based on the number of general practice consultations. Requirements for surveillance during various pandemic phases also need to be reviewed.