• Influenza is a highly contagious virus that causes widespread illness every year.
  • Immunisation is the most important way we can protect against the flu and reduce the number of flu infections and deaths.
  • Yearly immunisation is strongly recommended for older people and other people who are at risk of serious complications from the flu.
  • Influenza immunisation is recommended for all people from six months of age.
  • People who work or live with people who are at risk of serious complications should also be immunised to avoid spreading the flu.
  • The vaccine cannot give you the flu because it does not contain any live virus.

Immunisation is the best possible protection against influenza. It is the most important way we can reduce the number of influenza infections and deaths.

Influenza, commonly known as the flu, is caused by a highly contagious virus that is spread by contact with fluids from coughs and sneezes. Every year, influenza causes widespread illness in the community. 

An influenza epidemic occurs when an outbreak of the illness is widespread in a certain community. A pandemic occurs when the illness is more geographically widespread and on more than one continent. Influenza epidemics occur, on average, every three years. Pandemics have occurred only four times in the past 100 years.

Who should be immunised against influenza?

Immunisation is recommended for everyone aged six months and over. Some people are more at risk of complications from influenza and are eligible for free vaccination. People with an underlying medical condition or reduced immunity are most at risk and should be immunised against influenza. They include: 

  • anyone aged 65 years and older
  • pregnant women (at any stage of pregnancy)
  • all Aboriginal and Torres Strait Islander people aged from six months and over
  • people aged six months or older with:  
    • heart disease
    • chronic lung disease (including people with severe asthma who require frequent hospital visits)
    • chronic neurological conditions
    • impaired immunity
    • haemoglobinopathies (blood disorders caused by genetic changes)
    • diabetes
    • kidney disease
  • children on long-term aspirin therapy aged six months to 10 years
  • children aged from six months to under five years of age.

Immunisation is also recommended (but not necessarily free) for other people such as:

  • those who work with or live in close contact with people with an underlying medical condition or reduced immunity, such as:
    • health care workers
    • staff in long-term care facilities or nursing homes
    • people who live with, or care for someone who has a chronic illness or is aged over 65 years
    • carers of homeless people
    • workers, particularly those in workplaces that provide essential services
    • people who work with children
  • people with Down syndrome 
  • people who are obese (BMI greater than or equal to 30 kg/m2)
  • people who are addicted to alcohol 
  • people who are homeless
  • residents in nursing homes or other long-term care facilities
  • people involved in the commercial poultry and pig industry
  • people who provide essential community services 
  • anyone visiting parts of the world where influenza is circulating, especially if travelling in a group.

Some workplaces run annual immunisation programs for staff.

How the influenza vaccine works

Influenza viruses change every year because the influenza virus has a unique ability to change its surface structure. This means that even if you had influenza or an immunisation one year, your body’s immune system might be unable to fight the changed version of the virus that will be circulating the following year. 

Each year, a new vaccine is developed (usually called the seasonal vaccine) and is available for those who wish to be immunised. The seasonal influenza vaccine includes protection against four strains of influenza. 

Recent evidence suggests optimal protection against influenza occurs within the first three to four months following vaccination. Annual vaccination before the onset of each influenza season is recommended. In most parts of Australia this occurs from June to September. Immunisation from April provides protection before the peak season. While influenza continues to circulate, it is never too late to vaccinate. 

The influenza vaccine cannot give you influenza because it does not contain live virus. Some people may still contract influenza because the vaccine may not always protect against all strains of the influenza virus circulating in the community. 

An annual influenza vaccination is provided through the National Immunisation Program for most people in the community who are at an increased risk of serious complications. In Victoria, an annual vaccination against influenza is free for: 

  • children aged six months to less than five years of age
  • people who have medical conditions that put them at risk of serious complications of influenza
  • Aboriginal and Torres Strait Islander people aged from six months and over
  • pregnant women – at any stage of pregnancy
  • people 65 years and over.

Contact your doctor or immunisation provider for further information about eligibility. People not covered by these categories can also have an annual influenza immunisation, but it is not available for free. 

Influenza vaccines for different ages

Age restrictions apply to all influenza vaccine brands. There is a formulation for people aged under 65 years and formulations for people aged 65 years and older. Check with your immunisation provider that the right formulation is used for you or someone in your care.

Pregnancy and influenza immunisation

Pregnant women are at increased risk of complications from influenza. Influenza vaccine is strongly recommended and safe for pregnant women at any time during pregnancy. It can also be safely given while breastfeeding.

Influenza vaccination of pregnant women also protects infants against influenza for the first six months after birth due to transplacental transfer of antibodies from the vaccinated woman to the unborn baby.

Influenza pre-immunisation checklist

Before receiving the vaccine, make sure that you tell your doctor or nurse if you (or your child): 

  • are unwell (have a temperature over 38.5°C)
  • have had a serious reaction to any vaccine
  • have had a severe allergy to anything
  • are under six months of age
  • have had Guillain-Barré syndrome.

Possible side effects of the influenza vaccine

The influenza vaccine can cause side effects. In children under five years of age, these reactions may be more obvious. Common side effects of influenza vaccine include: 

  • drowsiness or tiredness
  • muscle aches
  • localised pain, redness and swelling at the injection site
  • occasionally, an injection-site lump (nodule) that may last many weeks but needs no treatment
  • low-grade temperature (fever).

Managing fever after immunisation

Common side effects following immunisation are usually mild and temporary (occurring in the first two days after vaccination). Specific treatment is not usually required. There are a number of treatment options that can reduce the side effects of the vaccine including: 

  • drinking extra fluids and not overdressing if there is a fever
  • although routine use of paracetamol after vaccination is not recommended, if pain and fever are present, paracetamol can be given – check the label for the correct dose or speak with your pharmacist, (especially when giving paracetamol to children).

Concerns about side effects

If the side effect following immunisation is unexpected, persistent or severe, or if you are worried about yourself or your child’s condition after a vaccination, see your doctor or immunisation nurse as soon as possible or go directly to a hospital.

Immunisation side effects may be reported to the SAEFVIC, the central reporting service in Victoria on 1300 882 924 (option 1). You can discuss how to report problems in other states or territories with your immunisation provider. 

It is also important to seek medical advice if you (or your child) are unwell, as this may be due to other illness rather than because of the immunisation.

Rare side effects of the influenza vaccine

There is a very small risk of a serious allergic reaction (anaphylaxis) to any vaccine. This is why you are advised to stay at the clinic or medical surgery for at least 15 minutes following vaccination in case further treatment is required. Apart from anaphylaxis, other extremely rare side effects include febrile convulsions in children.

A small increase in Guillain-Barré syndrome was seen in the US in 1976, but since that time, surveillance has shown that it is limited to one case for every million doses of influenza vaccine, if at all.

If any other reactions are severe and persistent, or if you are worried, contact your doctor for further information. 

Immunisation and HALO

The immunisations you may need are decided by your health, age, lifestyle and occupation. Together, these factors are referred to as HALO.

Talk to your doctor or immunisation provider if you think you or someone in your care has health, age, lifestyle or occupation factors that could mean immunisation is necessary. You can check your immunisation HALO using the downloadable HALO poster .

Where to get help



More information


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Immunisation basics

Timing and schedules

Immunisation throughout life

A-Z of immunisations and vaccines

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This page has been produced in consultation with and approved by: Department of Health and Human Services - RHP&R - Health Protection - Communicable Disease Prevention and Control Unit

Last updated: April 2019

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