WHO previously published pandemic preparedness guidance in 1999 and a revision of that guidance in 2005. Since 2005, there have been advances in many areas of preparedness and response planning. For example, stockpiles of antiviral drugs are now a reality and a WHO guideline has been developed to attempt to stop or delay pandemic influenza at its initial emergence. There is increased understanding of past pandemics, strengthened outbreak communications, greater insight on disease spread and approaches to control, and increasingly sophisticated statistical modeling of various aspects of influenza. Extensive practical experience has been gained from responding to outbreaks of highly pathogenic avian influenza. A (H5N1) virus infection in poultry and humans, and from conducting pandemic preparedness and response exercises in many countries. There is greater understanding that pandemic preparedness requires the involvement of not only the health sector, but the whole of society. In 2007, the International Health Regulations (2005) (IHR, 2005) entered into force providing the international community with a framework to address international public health concerns.
In light of these developments, WHO decided to update its guidance to enable countries to be better prepared for the next pandemic.