In April 2009, a new influenza A virus, pandemic (H1N1) 2009 influenza, was identified in Mexico and the United States of America. The NSW response was co-ordinated by the Public Health Emergency Operations Centre through an incident control structure that included planning, operations and logistics teams with designated roles and responsibilities for the public health response. The emphasis of public health action changed as the pandemic moved through three response phases: DELAY, CONTAIN and PROTECT. This article describes the NSW public health response to the 2009 influenza pandemic from the perspective of the NSW Department of Health. Paula J. SpokesA,C, Michelle A. CretikosA and John G. WardA ACommunicable Diseases Branch, NSW Department of Health BAIDS/Infectious Diseases Branch, NSW Department of Health CCorresponding author. Email: pspok@doh.health.nsw.gov.au community. The public health response used the framework described in the Australian Health Management Plan for Pandemic Influenza 2008.3 Management of the pandemic moved through three phases: DELAY (of the virus into Australia); CONTAIN (early identification of cases and contacts to contain transmission in the community); and PROTECT (identification of high-risk groups to protect those most at risk of severe illness) (Table 1). The public health response was co-ordinated through an incident management system that included an incident controller and separation of activities into three areas: planning, operations and logistics (Figure 1).4 DELAY and CONTAIN phases The first case of pandemic (H1N1) 2009 influenza in Australia was reported from Queensland on 8 May.5 The first NSW case was not identified until 20 May in a traveller returning from the USA.6 This case was considered non-infectious. Australia moved to the next response phase, CONTAIN, on 22 May in response to the identification of suspected community transmission in Victoria.7,8 Planning Planning for an influenza pandemic had been in progress in NSW since at least 2005. The NSW Interim Influenza Pandemic Action Plan 20059 and the Australian Health Management Plan for Pandemic Influenza 20083 formed the basis of the public health response to the pandemic. The National Action Plan for a Human Influenza Pandemic10 and the NSW Human Influenza Pandemic Plan11 described the inter-government and inter-agency responsibilities to this situation. A number of recent public health emergencies (including severe acute respiratory syndrome (SARS) and equine influenza) and events such as World Youth Day 2008 and exercises also contributed to NSW planning and preparedness for an influenza pandemic.12–17 The planning team co-ordinated a number of aspects of the public health response, including: • forward planning and forecasting • communication (web-based, media and written updates) • preparation and dissemination of situation reports on the progress and impact of the epidemic • surveillance