Abstract

On 25 April 2009, on the basis of the outbreak and spread of a novel influenza virus with pandemic potential, the World Health Organization (WHO) Director-General, Margaret Chan, announced a Public Health Emergency of International Concern (PHEIC) – the first declaration of its kind following the entry into force of the revised International Health Regulations (IHR) in 2007. Shortly thereafter, on 11 June 2009, the WHO elevated its pandemic alert level to Phase 6, indicating that the circulating influenza A (H1N1) virus had entered a pandemic phase.