Outbreak history on April 25

Historical outbreak-response milestones recorded on this calendar date, drawn from WHO Disease Outbreak News, CDC archives, and primary epidemiological literature.

• 2009

  WHO declares H1N1 influenza a PHEIC

  The WHO Emergency Committee declared the emerging H1N1 swine flu outbreak a Public Health Emergency of International Concern — the FIRST-ever PHEIC under the IHR (2005) framework. The declaration, made when the strain had been detected in the United States, Mexico, and Canada, was the inaugural test of the regulations that had come into force only two years earlier.

  Glossary: PHEIC

Browse the full outbreak history calendar for milestones across all dates.