For most people, influenza, or flu, causes fever, coughing, headaches, aches and pains, and fatigue. Flu illness can escalate and develop into life-threatening complications like pneumonia and respiratory failure. Each year scientists predict which strains of the flu virus are likely to affect which areas of the world. Vaccines are developed and then distributed annually to help build immunity against seasonal flu viruses so as to protect against flu and its potentially serious complications.
A flu pandemic can occur when a novel, non-human strain of the flu virus emerges, and a given population has little or no immunity against it. If the virus spreads throughout a given population and then spreads across national or geographical boundaries, it becomes a global threat— a flu pandemic.
Flu pandemics have happened four times before in recent history—in 1918, 1957, 1968, and 2009. And, the world is currently responding to the COVID-19 pandemic, and national health systems are being put to the test.
A key element of response is being able to distribute and administer vaccine efficiently and effectively. Influenza programs can support readiness now and in the future.
For more information on flu or pandemics, please visit:
Influenza News from the CDC
CDC International Influenza Updates
CDC Seasonal Flu Updates
- Increasing Seasonal Influenza A (H3N2) Activity, Especially Among Young Adults and in College and University Settings, During SARS-CoV-2...on November 29, 2021 at 4:16 pm
Increasing Seasonal Influenza A (H3N2) Activity, Especially Among Young Adults and in College and University Settings, During SARS-CoV-2 Co-Circulation
- CDC Tracking Flu in Young Adultson November 19, 2021 at 5:00 am
CDC Tracking Flu in Young Adults
- Increasing Flu Activity in Some States, Especially Among Young Adultson November 15, 2021 at 8:34 pm
Increasing Flu Activity in Some States, Especially Among Young Adults
- CDC Collaboration Improves Flu Vaccination Efforts in Latin America and the Caribbeanon November 10, 2021 at 5:32 pm
CDC Collaboration Improves Flu Vaccination Efforts in Latin America and the Caribbean
- CDC Update on A(H5N6) Bird Flu: How is the U.S. CDC Monitoring A(H5N6) Infections and Contributing to Global Pandemic Preparedness?on November 1, 2021 at 4:00 am
Ongoing global monitoring for respiratory viruses with pandemic potential has recently identified three new human infections with avian influenza A(H5N6) virus (or "A(H5N6) bird flu") in China.