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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. In the United States alone influenza results in an estimated:

  • 9.3 - 45

    million illnesses
    estimated annually
    since 2010*

  • 17 million

    lost workdays^

  • 91 million

    lost schooldays~

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

It's estimated that in the USA, about 1 in 18 children, 1 in 38 elderly and 1 in 45 adults3 who get influenza-like illnesses will seek medical attention, so the disease could be more widespread than we know.

Death from influenza is much more common among the elderly and the very young, but all ages are at risk for serious complications such as pneumonia, myocarditis, and inflammation of the brain or meninges.2

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. This is why we need new influenza vaccines each influenza season - and why we are always working to stay ahead of the mutating virus. The new virus strains generally appear first in Southeast Asia then travel to the rest of the world. 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.
Learn more about pandemic influenza

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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 2022)
^ Centers for Disease Control and Prevention. (n.d.). Influenza (Flu) in the Workplace. Retrieved from (Accessed October 2022)
~ Walgreens 2013 Flu Impact Report. (2013) Retrieved from (Accessed October 2022)

1. World Health Organization. Influenza (Seasonal) Fact Sheet, January 2018. Available online: (Accessed October 2022)
2. Public Health England. Immunisation against infectious disease: the green book. Chapter 19: Influenza, September 2022. Available online: (Accessed October 2022)
3. Fox, M. (2009, Feb.) Few in U.S. see doctor or get medication for flu: study. Retrieved from: (Accessed October 2022)
4. Centers for Disease Control and Prevention. Seasonal Influenza (flu). Prevent Flu.  (Accessed September 2022).
5. NHS Choices, Flu Vaccine FAQs. Accessed October 2022.
6. NHS, Vaccinations: (Accessed October 2022).
7. Centers for Disease Control and Prevention, How Flu Spreads. Found at (Accessed October 2022)
8. Centers for Disease Control and Prevention, The Flu: What To Do If You Get Sick found at (Accessed October 2022)
9. Centers for Disease Control and Prevention, Flu Symptoms & Complications. Found at (Accessed October 2022)


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