2009 H1N1 Pandemic Timeline
In 2009, a new H1N1 influenza virus emerged, causing the first global flu pandemic in 40 years. Below is a timeline of major events that took place during the 2009 H1N1 pandemic.
- First human infection with new influenza A H1N1 virus detected in California.
- Second human infection with the new influenza A H1N1 virus detected in California about 130 miles away from first infection, with no known connection to previous patient.
- First novel 2009 H1N1 flu infections were reported by CDC to the World Health Organization (WHO) through the U.S. International Health Regulations Program.
- CDC activated it’s Emergency Operations Center (EOC).
- Two additional human infections with 2009 H1N1 were detected in Texas, transforming the investigation into a multistate outbreak and response.
- CDC uploaded complete gene sequences of new H1N1 2009 virus to a publically-accessible international influenza database.
- The World Health Organization (WHO) declared a public health emergency of international concern.
- The United States Government declared 2009 H1N1 a Public Health Emergency of International Concern and CDC began releasing 25% of antiviral drugs needed to treat this new influenza virus from the federal stockpile.
- WHO Director-General raised the level of influenza pandemic alert from phase 3 to phase 4, based on data showing person-to-person spread and the ability of the virus to cause community-level outbreaks.
- The Food and Drug Administration (FDA) approves new CDC test to detect 2009 H1N1 infections
- WHO raised the level of influenza pandemic alert from phase 4 to phase 5, signaling that a pandemic was imminent, and requested all countries immediately activate their pandemic preparedness plans and be on high alert for unusual outbreaks of influenza-like illness and severe pneumonia.
Page last reviewed: May 8, 2019