WHO Pandemic Levels

Here is a quick look at the WHO's pandemic alert phases:

• Phase 1: A virus in animals has caused no known infections in humans.
• Phase 2: An animal flu virus has caused infection in humans.
• Phase 3: Sporadic cases or small clusters of disease occur in humans. Human-to-human transmission, if any, is insufficient to cause community-level outbreaks.
• Phase 4: The risk for a pandemic is greatly increased but not certain. The disease-causing virus is able to cause community-level outbreaks.
• Phase 5: Still not a pandemic, but spread of disease between humans is occurring in more than one country of one WHO region.
• Phase 6: This is the pandemic level. Community-level outbreaks are in at least one additional country in a different WHO region from phase 5. A global pandemic is under way.