What is Influenza
Influenza, commonly called the flu, is a contagious respiratory illness caused by influenza viruses. It affects the nose, throat, and lungs, and ranges from mild to severe. It’s distinct from the common cold, though the two are often confused because some symptoms overlap.
How influenza spreads
The virus spreads mainly through droplets produced when an infected person coughs, sneezes, or talks. These droplets can land in the mouths or noses of people nearby. It’s also possible to catch the flu by touching a surface that has the virus on it and then touching your face, though this is less common than airborne transmission.
Infected people can spread the virus before they even know they’re sick. This makes workplaces, public transport, and other shared spaces particularly effective environments for transmission.
Symptoms
Flu symptoms manifest within one to three days of exposure. They tend to come on suddenly rather than building gradually, which is one way to distinguish the flu from a cold. Common symptoms include fever, cough, sore throat, body aches, headache, fatigue, and sometimes vomiting or diarrhoea.
Recovery can stretch over two weeks, even in otherwise healthy people. During this time, energy levels are often significantly reduced, making it difficult to work effectively.
Flu season in Australia
Australia’s flu season runs from April to October, with activity typically peaking between June and September. The timing and severity vary from year to year, but the pattern is consistent enough that organisations can plan around it. This is why most workplace vaccination programs are scheduled in the earlier months of the season.
Influenza vs the common cold
People sometimes dismiss the flu as “just a bad cold,” but the two illnesses are caused by different viruses and differ in severity. Colds generally produce milder symptoms and resolve within a few days. Influenza hits harder and lasts longer. The flu can also lead to complications, particularly in older adults, young children, pregnant women, and people with certain underlying health conditions. More on this is covered on our flu complications page.
Vaccination
Annual vaccination is the primary method of protection against influenza. The vaccine is updated each year to match the strains expected to circulate. For information on how the vaccine works and common questions about side effects, see our page on flu vaccine side effects. The Australian Immunisation Handbook provides authoritative clinical guidance on influenza vaccination.
If you’re interested in vaccination for your workplace, Corporate Care runs onsite flu vaccination programs across Australia with AHPRA-registered Registered Nurse Immunisers. Request a quote to get started.
Last updated: 18 May 2026