WHO Pandemic Phases and Planning Goals

WHO pandemic phases and planning goals

Inter-pandemic period

Phase 1. No new influenza virus subtypes have been detected in humans. An influenza virus subtype that has caused infection may be present in animals. If present in animals, the risk of human infection or disease is considered to be low.

Ensure rapid characterization of the new virus
subtype and early detection, notification and
response to additional cases.

Phase 2. No new influenza virus subtypes have been detected in humans. However, a circulating animal influenza virus subtype poses a substantial risk of human disease.

Minimize the risk of transmission to humans;
detect and report such transmission rapidly if it
occurs.

Pandemic alert period

Phase 3. Human infection(s) with a new subtype, but no human-to-human spread, or at most rare instances of spread to a close contact.

Ensure rapid characterization of the new virus
subtype and early detection, notification and
response to additional cases.

Phase 4. Small cluster(s) with limited human-to human transmission but spread is highly localized, suggesting that the virus is not well adapted to humans.

Contain the new virus within limited foci or delay
spread to gain time to implement preparedness
measures, including vaccine development.

Phase 5. Larger cluster(s) but human-to human spread still localized, suggesting that the virus is becoming increasingly better adapted to humans, but may not yet be fully transmissible (substantial pandemic risk).

Maximize efforts to contain or delay spread, to
possibly avert a pandemic and to gain time to
implement pandemic response measures.

Pandemic period
Phase 6. Pandemic: increased and sustained
transmission in the general population.

Minimize the impact of the pandemic.

Actions taken during phase 6 will differ in affected versus non-affected areas

Source: WHO. Pandemic influenza preparedness and mitigation in refugee and displaced population, WHO guidelines
for humanitarian agencies. WHO/CDS/NTD/DCE/2006.2

Leave a Reply