WHO pandemic phases

On June 11, the World Health Organization declared a swine flu pandemic, the first global flu epidemic in 41 years. Infections in the United States, Europe, Australia, South America and elsewhere approached 30,000 cases.

Here’s a list of WHO pandemic phases and what each one means:

Phase 1: 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 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 other country in another WHO region.

Source: World Health Organization

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