Definition: The World Health Organization coordinates the world's response to pandemics. The pandemic phase is based on a scale of 1-6 defined by the World Health Organization. The director general of WHO is the person who decides the current pandemic phase.
- 1 Low risk of human cases, meaning little risk of pandemic flu. No human cases have occurred, simply a new virus has emerged in animals.
- 2 Higher risk of human cases. No human cases have occurred, simply a new virus has emerged in animals.
- 3 No, or very limited human-to-human transmission. Pandemic alert. New virus causes human cases.
- 4 Evidence of increased human-to-human transmission. Pandemic alert. New virus causes human cases.
- 5 Evidence of significant human-to-human transmission. Pandemic alert. New virus causes human cases.
- 6 Efficient and sustained human-to-human transmission. A pandemic is declared.
Examples: The world is currently in phase 3, a new virus has emerged and is infecting humans, but it is not yet very contagious nor is it spreading from person-to-person efficiently.