Past Influenza Pandemics
An influenza pandemic is a global outbreak of a new influenza A virus that is very different from current and recently circulating human seasonal influenza A viruses. Influenza A viruses are constantly changing, making it possible on very rare occasions for non-human influenza viruses to change in such a way that they can infect people easily and spread efficiently from person to person.
Recent Influenza Pandemics
Influenza Historical Timeline
Below is a historical timeline of major scientific and public health events and milestones in influenza prevention.
Influenza Pandemic Timelines
In 1918, a new influenza virus emerged. During this same time period World War I was taking place. The conditions of World War I (overcrowding and global troop movement) helped the 1918 flu spread. The vulnerability of healthy young adults and the lack of vaccines and treatments created a major public health crisis, causing at least 50 million deaths worldwide, including approximately 675,000 in the United States. Below is a historical timeline of major events that took place during this time period.
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.
