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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. It spreads easily from person to person1 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 deaths1. It is estimated that 10,000 deaths in England and Wales are attributable to influenza infections annually2. In the United States alone influenza results in an estimated:

  • 9.3 - 45

    million illnesses
    estimated annually
    since 2010*

  • 18 million

    medical visits in 2019-20 flu season*

  • 91 million

    lost schooldays
    in 2012-13 season~

Seasonal Influenza

CSL Seqirus is on the front line of influenza protection, helping guard against costly and life-threatening epidemics and pandemics. Vaccination is the most effective way to prevent influenza1.

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 hospitalisation 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 respiratory disease2. 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 complications2.

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.
Learn more about pandemic influenza

Frequently Asked Questions

Consumers should contact their health care professional for further advice.

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Our Products

CSL Seqirus is a reliable supplier of seasonal influenza vaccine with the ability to rapidly respond to pandemic threats. Our broad range of influenza vaccines help to safeguard people and communities around the world. You should speak to your healthcare professional for specific advice on influenza vaccination.

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Report an Adverse Event

To report a suspected side effect or adverse event, please visit our Report an Adverse Event page.

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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.

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* Centers for Disease Control and Prevention. (n.d.). Disease Burden of Influenza. Retrieved from (Accessed October 2020)
~ Walgreens 2013 Flu Impact Report. (2013) Retrieved from (Accessed October 2020)

1. World Health Organization. Influenza (Seasonal) Fact Sheet, January 2018. Available online: (Accessed October 2020)
2. Public Health England. Immunisation against infectious disease: the green book. Chapter 19: Influenza, August 2018. Available online: (Accessed October 2020)
3. Centers for Disease Control and Prevention. Seasonal Influenza (flu). Prevent Flu. Found at: (Accessed November 2020)
4. Centers for Disease Control and prevention, Quadrivalent Influenza vaccine. Found at: (Accessed November 2020)
5. Centers for Disease Control and Prevention, How Flu Spreads. Found at (Accessed November 2020)
6. Centers for Disease Control and Prevention, The Flu: What To Do If You Get Sick found at (Accessed November 2020)
7. Centers for Disease Control and Prevention, Flu Symptoms & Complications. Found at (Accessed November 2020)

GBR-FLU-0006 February 2021