Influenza

Key facts

  • Influenza is a viral infection. It can make your child very unwell, even if they are usually healthy.

  • Influenza can lead to serious conditions like severe lung infections (pneumonia) or swelling in the brain (encephalitis).

  • It is recommended that all children aged six months or older have an annual vaccination to protect them against influenza. Influenza vaccines are free for all children aged six months to under five years and can be given at the same time as age-specific vaccines. 

Last updated on 13 December 2024.

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When to vaccinate against influenza

It is recommended that children aged six months or older get an influenza vaccine every year.


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What is influenza?

Influenza is a viral infection. It can make your child very unwell, even if they are usually healthy.

Influenza usually begins with the sudden onset of fever, chills, a headache, dry cough, sore throat and feelings of fatigue and weakness. If it progresses, influenza can also cause dehydration or complications such as pneumonia or bronchitis. More serious complications can also occur, including secondary bacterial infections, as well as heart, blood and neurological abnormalities such as inflammation of the brain (encephalitis).

Babies and children under 5 years are more likely to get severe influenza. They are more likely than adults and older children to need treatment in hospital.1

Aboriginal and Torres Strait Islander children and children who have health conditions (such as asthma or a heart defect) are more likely to get so sick from influenza that they need treatment in hospital.

What will happen to my child if they catch influenza?

Usual symptoms

  • Children with influenza may get a fever, feel tired or lacking in energy (malaise), a headache, a dry cough, chills, muscle aches (myalgia), a runny nose and sneezing.
  • Some babies and children may vomit or have diarrhoea (watery poo). 

Rare symptoms

  • Children with influenza sometimes get acute bronchitis (swollen airways), croup (swelling in their voice box and windpipe that causes a bark-like cough), otitis media (ear infection that causes ear ache) and pneumonia (infected lungs).
  • Children can experience a fit (febrile convulsion) from influenza infection. One study found about four in 100 children who were treated in hospital for influenza had a febrile convulsion.2

Very rare symptoms

  • Very rarely, children with influenza can get swelling (inflammation) in their heart muscle (myocarditis), the lining of their heart (pericarditis), or their brain (encephalitis). They can also get swelling in their liver and brain (Reye’s syndrome). 
  • Very rarely, children can die from influenza. One study found between two and four children in every one million die from influenza.3 Because this number is hard to calculate accurately, the true number is likely higher. 
What vaccine will protect my child against influenza?

An influenza vaccine is the best way to protect your child against influenza.

As well as protecting your child from getting sick, an annual influenza vaccination helps protect the people around you and your child. If you don’t catch influenza, you can’t spread influenza. This community protection is especially important for vulnerable people, like young babies (less than six months old) who can’t get the vaccine, and people with low immunity.

Influenza vaccines protect your child against several types of influenza virus. The types of virus particles in the vaccine may change each year depending on which viruses are likely to be circulating.

When should my child be vaccinated?

If your child is six months or older, it is recommended they get an influenza vaccine every year. Influenza vaccines are free for all children aged six months to under five years.

If your child is aged between six months and nine years and is receiving the influenza vaccine for the first time, then it is recommended they have two doses, at least four weeks apart. The second year your child gets an influenza vaccine (and every year after that), they will only need one dose.

Your child can get an influenza vaccine either on its own or at the same time as their age-specific vaccinations. The best time to get an influenza vaccine is in April or May, before the influenza season, which is usually June to September.1

How does the influenza vaccine work?

The influenza vaccine protects against three or four types (or ‘strains’) of the influenza virus. It works by ‘training’ your body’s immune system to recognise and get rid of the influenza virus. The vaccine contains antigens, which are tiny, harmless fragments of the influenza virus. 

When your immune system detects the antigens in the vaccine, it produces proteins called antibodies. These antibodies are like soldiers that recognise and remember the influenza virus type (strain). If your child is ever exposed to the real influenza virus type, their immune system will recognise it quickly and fight it off using the antibodies it created after vaccination.4

It can take about two weeks for your body to develop enough antibodies to be protected against an influenza virus.
Influenza vaccines do not contain any blood products and are not ‘live’ vaccines. The inactivated antigens cannot replicate themselves or cause disease. 

How effective is the vaccine?

Overall, influenza vaccination is the most effective way to protect your child against the virus; however, the effectiveness of influenza vaccines can vary depending on which strains of the virus are present in the community.

Each year, the Australian Influenza Vaccine Committee follows the recommendations of the World Health Organization to decide which strains should be included in the vaccine to provide the best protection.

It is important for children over six months of age to get an influenza vaccine every year to ensure they are vaccinated against the strains of the virus that are likely to be circulating in that season. 

Available research shows influenza vaccination is effective at preventing around 53 per cent of children and adolescents (aged 6 months–17 years) from being hospitalised because of influenza.5

Will my child catch influenza from the vaccine?

No, there is no risk that your child will catch influenza because the vaccine does not contain the live virus that causes the disease.

What are the common reactions to the vaccine?
  • About 10 per cent of children (1 out of every 10) who have an influenza vaccine experience swelling, redness, and pain at the injection site that lasts one or two days.
  • Between 1 per cent and 10 per cent of people (1–10 out of every 100) who have an influenza vaccine get a fever, headache, tiredness or lack of energy (malaise) or muscle aches (myalgia) that last one or two days. 
Are there any rare and/or serious side effects to the vaccine?
  • About 0.0014 per cent of children under two years (14 out of every 1,000,000) who have an influenza vaccine have a fit (febrile convulsion).6,7 This happens when a baby or child’s temperature (fever) goes up suddenly. Febrile convulsions don’t have long-term effects on a child’s health and development.
  • About 0.0001 per cent of people (1 out of every 1,000,000) who get an influenza vaccine have a severe allergic reaction (anaphylaxis).8 
  • Less than 0.0001 per cent of people (1 out of every 1,000,000) who get an influenza vaccine get Guillain-Barré syndrome.1

If your child doesn’t seem to be getting better, or you are worried about them, you can get help from:

  • your doctor
  • your nearest emergency department
  • or by calling Health Direct on 1800 022 222.
What else can I do to protect my child from influenza?

Children need to get an influenza vaccine every year. This is because the types of influenza viruses circulating often change from year to year. Also, protection from an influenza vaccine generally lasts less than a year.

  1. National Centre for Immunisation Research & Surveillance. Influenza vaccines - Frequently Asked Questions. National Centre for Immunisation Research & Surveillance: Sydney, Australia. Available from: http://ncirs.org.au/ncirs-fact-sheets-faqs/influenza-vaccines-australians-faqs 
  2. Dawood, F.S., et al., Complications and associated bacterial coinfections among children hospitalized with seasonal or pandemic influenza, United States, 2003-2010.(Report). Journal of Infectious Diseases, 2014. 209(5): p. 686. Available from: https://academic.oup.com/jid/article/209/5/686/887068 
  3. Li-Kim-Moy, J., et al., Australian vaccine preventable disease epidemiological review series: Influenza 2006 to 2015.Communicable diseases intelligence quarterly report, 2016. 40(4): p. E482. Available from: https://www1.health.gov.au/internet/main/publishing.nsf/Content/cda-cdi4004f.htm 
  4. Australian Academy of Science. The science of immunisation: questions and answers. Canberra, 2021. Available from: https://www.science.org.au/education/immunisation-climate-change-genetic-modification/science-immunisation
  5. Boddington NL, Pearson I, Whitaker H et al. Effectiveness of influenza vaccination in preventing hospitalization due to influenza in children: a systematic review and meta-analysis. Clinical Infectious Diseases 2021;73:1722-32. Available from: https://doi.org/10.1093/cid/ciab270 
  6. Australian Technical Advisory Group on Immunisation (ATAGI), Australian Immunisation Handbook. 2018, Australian Government Department of Health: Canberra. immunisationhandbook.health.gov.au
  7. Hambidge, S.J., et al., Safety of Trivalent Inactivated Influenza Vaccine in Children 6 to 23 Months Old. JAMA, 2006. 296(16): p. 1990-1997. Available from: https://jamanetwork.com/journals/jama/article-abstract/203797 
  8. Australasian Society of Clinical Immunology and Allergy (ASCIA), Guidelines: vaccination of the egg-allergic individual. 2017, ASCIA: Sydney, Australia. Available from: https://www.allergy.org.au/hp//papers/vaccination-of-the-egg-allergic-individual