English: The information in this table comes from the WHO Pandemic Influenza Phases, revised in 2009. The Pandemic Influenza Phases (2009) are described in several locations, including:
No animal influenza virus circulating among animals have been reported to cause infection in humans.
Phase 2
An animal influenza virus circulating in domesticated or wild animals is known to have caused infection in humans and is therefore considered a specific potential pandemic threat.
Phase 3
An animal or human-animal influenza reassortant virus has caused sporadic cases or small clusters of disease in people, but has not resulted in human-to-human transmission sufficient to sustain community-level outbreaks.
Phase 4
Human to human transmission of an animal or human-animal influenza reassortant virus able to sustain community-level outbreaks has been verified.
Phase 5
The same identified virus has caused sustained community level outbreaks in two or more countries in one WHO region.
Phase 6
In addition to the criteria defined in Phase 5, the same virus has caused sustained community level outbreaks in at least one another country in another WHO region.
Post peak period
Levels of pandemic influenza in most countries with adequate surveillance have dropped below peak levels.
Post pandemic period
Levels of influenza activity have returned to the levels seen for seasonal influenza in most countries with adequate surveillance.
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{{Information |Description={{en|1=The information in this table comes from the WHO Pandemic Influenza Phases, revised in 2009. The Pandemic Influenza Phases (2009) are described in several locations, including: *[http://www.who.int/csr/disease/avian_influ