Seasonal influenza vaccines: Questions and answers for consumers

15 April 2015
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Influenza virus causes infections in the throat, nose, airways and sometimes the lungs. Symptoms usually develop suddenly and typically include fever, tiredness, chills, muscle aches, headache, cough, poor appetite, sneezing and runny nose.

The influenza virus can cause mild to severe illness, and at times cause complications such as pneumonia and bronchitis, which require hospitalisation and can sometimes lead to death. Influenza can also make some underlying medical conditions worse.

The seasonal influenza vaccine is an annual vaccination that protects against the influenza virus.

The influenza vaccine exposes your immune system to the virus without the risk of catching the disease. When your immune system encounters a virus for the first time, it creates an antibody specifically designed to fight that virus. Your immune system retains a memory of this antibody and is able to rapidly release thousands of copies the next time it encounters the virus. As your immune system is able skip the process of producing a new antibody, it is able to act much faster and prevent infections before they start causing symptoms.

Some viruses, like the seasonal influenza virus, change very quickly and so your immune system does not recognise it the next time it's exposed and must create a new antibody. Making a new antibody takes time, so if you encounter the influenza virus without having been first vaccinated, your immune system will not be able to create the new antibody quickly enough to prevent infection.

Influenza vaccines change each year because the virus is constantly changing. As a result, the decision about the composition and production of the influenza vaccines happens on an annual basis for both the southern and northern hemispheres.

The Therapeutic Goods Administration (TGA) works with the Australian Influenza Vaccine Committee (AIVC) and the World Health Organization (WHO) to determine which strains of influenza should be included in the annual vaccine.

The TGA is responsible for deciding which strains are included in influenza vaccines for Australia. The TGA takes advice from AIVC, who consider recommendations from WHO as well as analyse data on virus circulation in Australia.

For a description of the TGA's role in the approval of the composition of seasonal influenza vaccines, see the annual Sourthern Hemisphere production and regulatory approval timeline.

In Australia, influenza vaccines are regulated by the TGA under the Therapeutic Goods Act 1989 (the Act). All vaccines must be entered in the Australian Register of Therapeutic Goods (ARTG) before they can be imported into, supplied in, or exported from Australia.

For a vaccine to be entered in the ARTG, a sponsoring company is required to make an application to the TGA and provide data to support the quality, safety and efficacy (effectiveness) of the product. This data is rigorously evaluated by the TGA to ensure the benefits of using the vaccine outweigh the risks.

The TGA also undertakes a batch release and batch testing programme for the influenza vaccine. Under this program, the TGA assesses the production data, quality control data, sterility and potency of each batch of vaccine before it's released onto the Australian market.

If you or someone you are caring for experiences an unexpected side effect from the influenza vaccine, or any other vaccine, please speak to a health professional in the first instance.

You can also report the side effect to the TGA to help us monitor the safety of vaccines. When people tell us about their experiences using a particular medicine or vaccine, it helps us to understand more about the possible side effects that may be previously unknown.

If you would like to read more about the influenza vaccine, including who is eligible for vaccination under the National Immunisation Program and specific information for different age groups and populations, please visit the Department of Health's Immunise Australia Program website.