WHO Phase 4 Described

DemFromCt has a helpful overview (including charts) of the WHO's recent decision to raise the pandemic alert to phase four.  Here is a brief excerpt:

. . .   There's a confirmed human outbreak overseas (several, actually - US, Canada, Spain and Mexico). And to clarify things further, WHO has redefined what their phases mean:

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. [my bold]

The Wall Street Journal also has some helpful discussion of the situation here.