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Influenza - the flu - is familiar to all of us. It's so common, in fact, that we often forget how serious it can be.
Influenza is an acute viral respiratory infection which can cause mild to severe disease1. It spreads easily from person to person2 including at home, at school, at work and other crowded areas such as at the supermarket or on the train to name a few.

Each year, influenza causes 3 to 5 million cases of severe illness around the world and about 290,000 to 650,000 respiratory deaths2. Since 2010, up to 61,000 deaths every year in the U.S. are estimated to be the result of Influenza3. In the United States alone influenza results in an estimated:

  • 9.3 - 45 million

    illnesses estimated annually since 20103

  • >16.5 million

    medical visits in 2018-19
    flu season3

  • 91 million

    lost schooldays4

Seasonal Influenza

CSL Seqirus is on the front line of influenza protection, helping guard against costly and life-threatening epidemics. Vaccination is the most effective way to prevent influenza2.

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More dangerous than you might think

Most people who get sick with influenza will have a mild illness. Some people, however, are more likely to get flu complications that can result in hospitalization and sometimes death. High risk groups include people over 65 years of age and older, young children, pregnant women and people with chronic illnesses such as diabetes, heart disease and severe asthma. Pneumonia, bronchitis, sinus infections and ear infections are examples of flu-related complications. Individuals 65 years and older are at higher risk for influenza-related complications. Influenza can also make certain chronic health conditions worse.5

Our bodies and the influenza virus are in a never-ending race. As our immune system evolves to avoid infection, the virus adapts to evade our immune system. Influenza spreads best when temperatures and humidity are low, so the flu season coincides with the winter months in all different parts of the globe. This is why we need new influenza vaccines each influenza season - and why we are always working to stay ahead of the mutating virus.

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Report an Adverse Event

To report a suspected side effect or adverse event, for CSL Seqirus products in the United States contact:
Phone: +1 855 358 8966

Or VAERS – Vaccine Adverse Event Reporting System
Phone: 1-800-822-7967 or

Visit our Report an Adverse Event page for more information.

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Pandemic Response Solutions™

When it comes to the next influenza pandemic, experts agree it’s not a matter of if, but when. CSL Seqirus partners with governments around the world to prepare for pandemic threats, with our portfolio of pandemic vaccines and our manufacturing facilities ever-ready for rapid response.

Learn more
  1. Centers for Disease Control. About Flu. Available online: (Accessed August 2020)
  2. World Health Organization. Influenza (Seasonal) Fact Sheet, January 2018. Available online: (Accessed August 2020)
  3. Centers for Disease Control and Prevention. (n.d.). Disease Burden of Influenza. Retrieved from (Accessed August 2020)
  4. Walgreens 2013 Flu Impact Report. (2013) Retrieved from (Accessed August 2020)
  5. Centers for Disease Control and Prevention. People at high Risk for Flu Complications. (Accessed August 2020)
  6. Centers for Disease Control and Prevention. Seasonal Influenza (flu). Healthy Habits to Help Prevent Flu. (Accessed August 2020).
  7. Centers for Disease Control. Quadrivalent Influenza Vaccine, Available online: (Accessed August 2020)
  8. Centers for Disease Control and Prevention. Flu Vaccine with Adjuvant. Found at (Accessed August 2020)
  9. Centers for Disease Control and Prevention. Seasonal Influenza (flu). Key Facts About Seasonal Flu Vaccine. Found at (Accessed August 2020).
  10. Centers for Disease Control and Prevention, How Flu Spreads. Found at (Accessed August 2020)
  11. Centers for Disease Control and Prevention, The Flu: What To Do If You Get Sick found at (Accessed August 2020)
  12. Centers for Disease Control and Prevention, Flu Symptoms & Complications. Found at (Accessed August 2020)