WHO Upgrades Pandemic Alert to Phase 4

The Emergency Committee, established in compliance with the International Health Regulations (2005), held its second meeting today to consider whether or not to raise the pandemic threat level.

After considering available epidemiological data on confirmed outbreaks of H1N1 swine influenza in the United States, Mexico, and Canada and reports of possible spread to additional countries, the Committee and Director General decided to change the pandemic alert to Phase 4. As further information becomes available, WHO may decide to either revert to phase 3 or raise the level of alert to another phase.

WHO also said that given the widespread nature of the virus, containment is not possible and health authorities should focus on mitigation efforts. No travel or trade restrictions have been imposed at this time, though ill individuals should delay travel and those feeling ill after traveling should seek medical care.

WHO's explanation of Phase 4:
"Phase 4 is characterized by verified human-to-human transmission of an animal or human-animal influenza reassortant virus able to cause “community-level outbreaks.” The ability to cause sustained disease outbreaks in a community marks a significant upwards shift in the risk for a pandemic. Any country that suspects or has verified such an event should urgently consult with WHO so that the situation can be jointly assessed and a decision made by the affected country if implementation of a rapid pandemic containment operation is warranted.

Phase 4 indicates a significant increase in risk of a pandemic but does not necessarily mean that a pandemic is a forgone conclusion."


See the Statement by WHO Director-General, Dr Margaret Chan: http://www.who.int/mediacentre/news/statements/2009/h1n1_20090427/en/index.html

See the WHO Pandemic Alert Site:
http://www.who.int/csr/disease/avian_influenza/phase/en/index.html

See the WHO site:
http://www.who.int/en/