Influenza

What is it?

Influenza viruses are single stranded RNA orthomyxoviruses which can cause acute viral infections of the respiratory tract. Infections are often classified according to the type of influenza virus responsible for the infection, typically A, B, C or D. Influenza types A and B are more commonly responsible for causing severe disease. Influenza A can be further subtyped based on the differences in surface antigens.

What to look for

The incubation period of influenza disease is 1 to 4 days with typical symptoms including fever, headache, myalgia (muscle aches), lethargy (tiredness), coryza (runny nose), sore throat and cough. Gastrointestinal symptoms such as nausea, vomiting and diarrhoea can also occur. Children with influenza will often present with symptoms of croup.

Most influenza infections will resolve within 2 to 7 days. However, complications including otitis media (ear infections), secondary bacterial pneumonia (lung infections) and encephalitis (brain inflammation) can prolong the illness and disease outcomes.

How is it transmitted?

Influenza is highly contagious. A person is infectious from a day before their symptoms begin until 3 to 5 days after the illness finishes. Children may be infectious for longer, up to 2 weeks after the illness, and immunocompromised individuals can transmit the virus for months. Transmission is via respiratory droplets, aerosol or through direct contact with the respiratory secretions of an infected person.

Epidemiology

Influenza disease can occur as sporadic cases, as an epidemic or as a pandemic. Whilst outbreaks more commonly occur in the winter months in temperate climates, there is a greater variation seen in the timing of cases in the tropics.

Aged care facilities, health care facilities and childcare centres are well recognised as high‑risk areas for influenza outbreaks.

Pregnant people, children under 5 years of age, those aged over 65 years, people with underlying medical conditions, and Aboriginal and Torres Strait Islander peoples carry the highest rates of morbidity and mortality in Australia.

Prevention

Annual influenza vaccination is recommended for everyone 6 months of age and older. Because the circulating strains of influenza virus change each year, influenza vaccines are updated annually to provide the most effective protection against disease.

Influenza vaccines are provided for free on the National Immunisation Program (NIP) for high‑risk groups, including: 

• children aged 6 months – < 5 years
• all adults ≥ 65 years of age
• specific populations aged 5–64 years who are at a greater risk of developing complications from influenza (pregnant people, First Nations people, and those with certain medical risk factors). 

Those aged 5 to 64 years who do not qualify for funded vaccines can purchase vaccines privately through some councils, GPs and pharmacies.

Healthy children (6 months – < 2 years) and children with a specified medical condition (6 months – < 9 years) who are receiving the influenza vaccine for the first time should receive 2 doses, 4 weeks apart. Most individuals aged 6 months and older who are receiving the influenza vaccines for the first time since haematopoietic stem cell transplant (HSCT), solid organ transplant (SOT) or CAR T-cell therapy should also receive 2 doses, 4 weeks apart (the exception is those who receive adjuvanted or high-dose vaccines, where only 1 dose should be received).

Different vaccines

Standard injected vaccines

The injected influenza vaccines available in Australia are inactivated, meaning that they cannot replicate and cause influenza disease. They can be cell‑based or egg‑based depending on how they are manufactured (see Commonly asked questions below for more information).

Live-attenuated influenza vaccines (LAIV)

The LAIV available in Australia (FluMist) is inhaled intranasally instead of requiring intramuscular or subcutaneous injection (refer to Resources section below for administration instruction). It is considered to have equivalent effectiveness compared with standard injected vaccines. Due to the risk of vaccine-associated disease, LAIVs are contraindicated in individuals with moderate to severe immunocompromise. They are registered for use in children aged 2 to 17 years and are available for private purchase Australia-wide and through some state-based programs (varying age group eligibility). Information on each state-based program is linked below:

• New South Wales
• Queensland
• South Australia
• Western Australia

MVEC have developed the following printable resource for further guidance: Nasal spray influenza vaccine: information for families

Table 1: The influenza virus strains included in the 2026 seasonal influenza vaccines

Adjuvanted and high‑dose vaccines

Due to a gradual decline in effectiveness of the immune system of older people (a process known as immunosenescence) immunity following vaccination with standard influenza vaccines can be suboptimal. In addition, those aged 65 years and older have the highest rates of influenza disease burden and associated complications including pneumonia and death. Therefore, to increase the immune response adjuvanted (Fluad) or high‑dose (Fluzone High‑dose) influenza vaccines are the preferred vaccines for the older population.

Vaccine brand according to age

Table 2: The 2026 influenza vaccine brand recommendations according to age (adapted from ATAGI statement on the administration of seasonal influenza vaccines in 2026)

* 2 doses, minimum of 4 weeks apart, should be given to healthy children aged 6 months to < 2 years and children aged 6 months to < 9 years with a specified medical condition in the first year of receiving the influenza vaccine, a single dose is recommended in subsequent years.
^ NIP funding only for First Nations people, pregnant people and people with certain medical risk factors.
# Adjuvanted or high‑dose quadrivalent influenza vaccines are preferentially recommended for people adults ≥ 65 years
Ω Vaxigrip/ Flucelvax /Fluzone/Influvac are registered for use in people aged ≥ 65 years, however adjuvanted or high‑dose vaccines are the preferred vaccines for this age group.
β 2 doses are recommended in the first year following solid organ transplant (SOT) or haematopoietic stem cell transplant (HSCT) regardless of history of influenza vaccination due to immunosuppression. The exception to this is in individuals receiving an adjuvanted or high‑dose influenza vaccine where only 1 dose is recommended.
shaded boxes indicate vaccines funded under the NIP for eligible individuals.
shaded boxes not registered for use in this age group.
shaded boxes indicate adjuvanted or high‑dose vaccines
shaded boxes indicate live-attenuated vaccines, which are contraindicated for pregnant women and people who are immunocompromised.

Expected side effects

Common side effects following vaccination include pain, redness and swelling at the injection site as well as fever, malaise and myalgia. Symptoms usually occur within the first 24 to 48 hours following immunisation. Injection site reactions are reported more commonly following high-dose or adjuvanted influenza vaccines compared with standard injected influenza vaccines.

Side effects following LAIV include rhinorrhoea (runny nose) or blocked nose, mild headache, tiredness or reduced appetite.

Precautions

It is estimated that vaccination against influenza can result in one case of Guillain–Barré syndrome (GBS) per 1 million doses of vaccine administered. However, the risk of GBS occurring post influenza infection is approximately 15 times higher than this. For more information refer to MVEC: Guillain–Barré syndrome.

Clinical trials of LAIV demonstrated an increased rate of wheeze post-vaccination in children less than 2 years of age. However, GRADE review suggests LAIV and inactivated influenza vaccine (IIV) share a similar safety profile in people with asthma and/or recurrent wheeze regardless of severity. As a precaution, MVEC recommends that children who have had acute wheeze/asthma symptoms in the preceding 72 hours should postpone vaccination with LAIV until stable, or alternatively, receive an IIV to avoid any delay in protection.

Commonly asked questions

Do seasonal influenza vaccines protect against ‘bird flu’ (avian influenza)?

Avian influenza is caused by different influenza A viruses that are not included in the seasonal influenza vaccines. Therefore, seasonal influenza vaccines do not protect against avian influenza. However, receipt of seasonal influenza vaccines is still recommended because it will reduce the risk of co‑infection with both avian influenza and seasonal influenza. This limits the theoretical chance of virus re-assortment (two different viruses combining to form a new virus).

When is the ideal time to be immunised against the flu?

Annual vaccination before the onset of influenza season is recommended for all individuals 6 months of age and older. The peak period of circulating influenza disease in Australia is typically June to September. However, out of season cases can and do occur. Optimal protection against influenza occurs within the first 3 to 4 months following vaccination. It is never too late in the season to vaccinate.

Pregnant women can safely receive the influenza vaccine during any stage of pregnancy. Where a pregnancy crosses over seasons, some pregnant women may be recommended to receive 2 influenza vaccines, one from each year.

Do healthy people need to be immunised against influenza?

Influenza can be a very serious disease resulting in hospitalisation and death. Even in cases where disease and its complications are not severe, it can cause a great inconvenience for the individual, including the cost of GP visits and medications, as well as time off work for themselves or to care for their sick child.

In some cases, a person may not get severe disease but infection can be spread to other people. This can be significant when it is spread to those who are too young to be immunised or are at higher risk of complications of disease.

If an individual has had confirmed influenza disease this year, are they still recommended to receive an influenza vaccine and when should they receive it?

Vaccination is still recommended for someone with a history of confirmed influenza infection as the vaccine protects against multiple strains of influenza disease. The influenza vaccine can be administered as soon as the patient has recovered from their illness.

For those receiving LAIV, an interval of 48 hours is recommended between completing antiviral therapy and being vaccinated.

Can the influenza vaccine be given at the same time as other vaccines?

Yes, influenza vaccines may be co‑administered with any other vaccine on the same day. This includes live‑attenuated vaccines (e.g. measles and varicella), shingles vaccination (Shingrix) and the vaccines recommended in pregnancy (influenza, pertussis, RSV +/- COVID‑19) can all be co‑administered.

If a patient received a 2025 influenza vaccine at the end of the season in early 2026, do they still need a 2026 influenza vaccine?

Yes. An updated influenza vaccine is still recommended in order to provide protection against this year’s circulating strains. A minimum interval of 4 weeks is recommended.

How many doses of influenza vaccine are recommended this year for children who were recommended 2 doses last year but missed the second dose?

Only 1 dose is required in this instance. If the second dose was inadvertently missed, it does not require catch up and only 1 dose is required in future years.

Are influenza vaccines safe for people with allergies?

Egg allergy
Based on prospective and retrospective studies of influenza vaccination in those with and without egg allergy (including egg anaphylaxis), the presence of egg allergy does not increase the risk of allergic reactions to the influenza vaccine. Egg‑based influenza vaccines (whether inactivated or live-attenuated) can be administered in community vaccination clinics (which may or may not have direct medical practitioner supervision), General Practitioner surgeries or immunisation clinics as a single dose followed by the recommended 15‑minute observation period. Individuals with egg allergy/anaphylaxis can safely receive egg-based influenza vaccines; it is not necessary to preferentially administer cell‑based influenza vaccines in this patient group.

Latex allergy
All influenza vaccines available under the NIP are latex free meaning that people with a latex allergy can safely be vaccinated.

For further queries on influenza vaccination, please contact us via our immunisation support.

Resources

• FluMist: Nasal spray influenza vaccine: information for families (PDF for printing)
• FluMist administration instructions (video)
• ATAGI statement on the administration of seasonal influenza vaccines in 2026
• TGA: AIVC Recommendations for the Composition of Influenza Vaccines for Australia in 2026
• Australian Centre for Disease Control: Seasonal flu (seasonal influenza)
• Australian Immunisation Handbook: Influenza
• Australasian Society of Clinical Immunology and Allergy: Vaccination of the egg allergic individual