Pandemic Alert at Phase 5

29 04 2009

The World Health Organization (WHO) raised the pandemic alert for the second time in two days.  It’s now at phase 5. 


Image: World Health Organization



Edited for brevity, this is how WHO explains the phases:

  • In nature, flu viruses circulate continuously among animals, especially birds.  In Phase 1 no viruses circulating among animals have been reported to cause infections in humans.
  • In Phase 2 an animal flu virus circulating among domesticated or wild animals is known to have caused infection in humans, and is considered a potential pandemic threat.
  • In Phase 3, an animal or human-animal flu 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 and/or to cause a pandemic.
  • 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.  Phase 4 indicates a significant increase in risk of a pandemic but does not necessarily mean that a pandemic is a forgone conclusion.
  • Phase 5 is characterized by human-to-human spread of the virus into at least two countries in one WHO region. While most countries will not be affected at this stage, the declaration of Phase 5 is a strong signal that a pandemic is imminent and that the time to finalize the organization, communication, and implementation of the planned mitigation measures is short.
  • Phase 6, the pandemic phase, is characterized by community level outbreaks in at least one other country in a different WHO region in addition to the criteria defined in Phase 5. Designation of this phase will indicate that a global pandemic is under way.

Technology, partnered with the work done by health experts on SARS and avian flu over the past few years, allows WHO to track the birth of a pandemic in real time.

They’re watching to see how it’s transmitted, the spectrum of disease in various populations (different age groups, cultures, and levels of medical care, etc), and how the virus itself may be changing, or mutating.

Dr. Margaret Chan, Director-General of WHO, says that, “All countries should immediately activate their pandemic preparedness plans. Countries should remain on high alert for unusual outbreaks of influenza-like illness and severe pneumonia.

“This change to a higher phase of alert is a signal to governments, to ministries of health and other ministries, to the pharmaceutical industry and the business community that certain actions should now be undertaken with increased urgency, and at an accelerated pace.”



One response

11 06 2009
H1N1 Moves to Phase 6 « PKIDs Blog

[…] H1N1 Moves to Phase 6 11 06 2009 After weeks of saying it without saying it, today WHO is moving the pandemic scale from phase 5 to phase 6. […]

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