Influenza Facts

Influenza (The Flu)

Influenza or ‘the flu’ is a highly contagious disease caused by infection from influenza type A or B (or rarely C) virus. These viruses infect the upper airways and lungs.

The flu is highly contagious and occurs year round but peaks each year from May to September.

Flu is not the same as a common cold, and can be a serious illness. For some people, such as the elderly and those with underlying medical conditions, the flu can cause serious complications which require hospitalisation. It can sometimes lead to death.

Flu is usually spread through infected people coughing and sneezing, which temporarily contaminates the surrounding air and surfaces with infected droplets. You can reduce the risk of infection by getting vaccinated and practising good hand and respiratory hygiene.

Occasionally there have been worldwide outbreaks of flu, known as flu pandemics, which have occurred with the global spread of a new type of flu virus.

Signs and Symptoms:

Symptoms usually appear 1–3 days after being infected. A person can spread flu to others 1–2 days before they become unwell and up to 5 days after symptoms develop.

The symptoms of influenza can include:

  • fever
  • dry cough
  • muscle and joint pain
  • tiredness/extreme exhaustion
  • headache
  • sore throat
  • stuffy nose.

Most people recover within a week, although a cough and tiredness may persist.


Generally, uncomplicated flu is managed by simply resting in bed, drinking plenty of fluids (particularly water) and taking over-the-counter medication to help relieve the symptoms.

Antiviral medications reduce the length of time symptoms last and help people return to their daily routines earlier. These medications are most effective if they are started within 48 hours of flu symptoms appearing.

See your doctor or call 13 HEALTH (13 43 25 84) if you:

  • are concerned about your symptoms
  • are in a high-risk group
  • have a cough and high fever (38 degrees Celsius or more) that is not improving.

The flu can spread from person to person by:

  • droplets spread from an infected person’s coughs or sneezes (these droplets generally travel less than 1 metre)
  • touching surfaces contaminated by infected droplets (including hands, phones, keyboards and door handles) and then touching your mouth, nose or eyes.

Flu viruses can survive on some hard surfaces for several hours. You should regularly clean frequently touched surfaces such as door handles, taps, tables, benches and fridge doors. Flu viruses can be removed with normal household detergents.


Good hygiene is essential to protect yourself and others:

  • stay home when you are sick
  • wash your hands regularly with soap and water or use an alcohol based hand gel
  • wash your hands prior to touching your eyes, nose and mouth
  • use a tissue, or the inside of your arm, when you cough and sneeze
  • throw tissues away immediately and wash hands
  • don’t share items such as cigarettes, cups, lipstick, toys or anything which has come into contact with the mouth or nose
  • stay at least 1 metre away from people who have flu-like symptoms
  • clean frequently touched surfaces regularly, such as door handles, taps, tables, benches and fridge doors.


Being vaccinated gives you protection against flu by building immunity to the virus and preventing transmission of the virus to other people.

Vaccination is required annually, as immunity from the vaccine decreases over time and the vaccine can change each year to cover the current virus strains. The best time to be vaccinated against flu is between March and May, before the flu season starts. Vaccination usually takes up to 2 weeks to be effective.

Vaccinations can be given to anyone aged 6 months or older, and is strongly recommended for people at higher risk of developing complications.

High-risk groups:

  • All adults aged >65 years of age
  • Pregnant women during any trimester
  • Aboriginal and Torres Strait Islander people aged >15 years of age
  • Aboriginal and Torres Strait Islander children aged 6 months to <5 years of age
  • Individuals >6 months of age with medical conditions predisposing them to severe influenza.

If you are in a high-risk group, you can be vaccinated for free under theImmunise Australia program.

If you don’t have access to the free vaccine, you can arrange to be vaccinated by a doctor or immunisation nurse at your local medical centre. Some community pharmacies may offer a private flu vaccination service. Check with your local council to see whether they have free immunisation clinics. Some employers may offer free flu vaccinations for staff.

The vaccine does not contain live flu viruses and cannot cause flu. However, some people may experience mild flu-like symptoms for up to 48 hours as their immune system responds to the vaccine. Serious reactions to immunisation are rare. While some people may experience mild side effects such as pain, swelling and redness at the injection site, these usually resolve quickly. Immediate allergic reactions to flu vaccine are rare. People who are allergic to eggs are no longer excluded from influenza vaccinations and should discuss their egg allergy and vaccination with their doctor.

If you experience any symptoms that concern you, call 13 HEALTH or your doctor / immunisation provider.

Seasonal influenza vaccine formulation

There are two types of inactivated influenza vaccines available in Australia. These are the three component Trivalent Influenza Vaccine (TIV) and the four component Quadrivalent Influenza Vaccine (QIV).

In 2016 the National Immunisation Program is distributing government-purchased QIV. TIV is available for purchase in the private market.

The influenza vaccine is updated each year to reflect virus strains circulating around the world in the last 12 months.

The antigens contained in the 2016 quadrivalent influenza vaccine:

  • an A/California/7/2009 (H1N1)pdm09-like virus
  • an A/Hong Kong/4801/2014 (H3N2)-like virus
  • a B/Brisbane/6062008-like virus
  • a B/Phuket/3073/2013-like virus.

The antigens contained in the 2016 trivalent influenza vaccine:

  • A/California/7/2009 (H1N1)pdm09 like virus
  • A/Hong Kong/4801/2014 (H3N2) like virus
  • B/Brisbane/60/2008 (B/Brisbane/60/2008 – like virus

World Health Organization (WHO) influenza experts select the influenza strains for the southern hemisphere season each year. Their selection is usually accurate but it is never entirely possible to know what strains will circulate until well into the influenza season. The QIV contains the same strain antigens as TIV with the addition of an extra flu B strain.

Health outcome:

Most people recover from the flu within a week, although a cough and tiredness may persist. Flu can sometimes lead to severe complications including pneumonia.

For young children and the elderly, flu is one of the most common vaccine preventable causes of hospitalisation.

Help and assistance:

For more information:

If you are in an emergency situation, call 000

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