Influenza surveillance and immunisation in New Zealand, 1997–2006

Background  The national influenza surveillance in New Zealand is an essential public health component for assessing and implementing strategies to control influenza. Objective  The aim of this study is to report the national influenza surveillance data collected during 1997–2006 in terms of the community disease burden, circulating viral strains, hospitalisations, mortality, and immunisation coverage. Methods  The national influenza surveillance system includes sentinel general practice surveillance, laboratory-based surveillance, and hospital admission and mortality surveillance and immunisation coverage. The results obtained during 1997–2006 were analysed. Results  When the last 10 years were compared to the previous years, sentinel general practice surveillance recorded a decreasing trend of influenza-like illness rates in the community. Sentinel surveillance also showed that children aged 0–4 years were the most affected. Influenza-related hospitalisation surveillance reported an increasing trend of hospital admissions particularly in children aged 0–19 years. Introduction of routine influenza vaccination among the New Zealand elderly was associated with a significant decrease of influenza-related mortality. Conclusions  This report demonstrates that an integrated virological and epidemiological surveillance system for influenza is essential for monitoring the disease burden, identifying circulating strains, guiding effective vaccination and planning for a potential pandemic.