Flu and you – what you need to know in 2025

The 2025 influenza (flu) season is upon us, with vaccination rates remaining alarmingly low and older Australians especially vulnerable.

So, as Australia heads into its annual flu season, what should you do to keep yourself and your loved ones safe, and what advice do our flu experts have for you?

Hudson Institute of Medical Research is a leader in inflammation research and viral infection scientist, Associate Professor Michelle Tate says small children and people over the age of 65 are the groups most likely to be adversely affected.

She says Australia is undergoing a significant demographic transformation, with the population aged 65 and older rapidly increasing.

Who is most at risk from flu in 2025?

“Globally, this trend is even more pronounced: for the first time in recorded history, adults over the age of 60 now outnumber children under five, and it will only accelerate, with the number of older adults projected to double by 2050.”

Working alongside A/Prof Tate is a team of inflammation researchers including Dr Alison West, who believes this demographic shift will challenge health systems worldwide, particularly in the prevention and management of age-related diseases.

“A key biological contributor to this increased vulnerability is immunosenescence – the progressive decline in immunity that comes with age – which reduces the body’s ability to prevent, control, and recover from infections.” Dr West said.

“From approximately age 20 onward, the immune system begins to lose resilience and this becomes clinically significant around age 50,” she said. “Older adults are thus more likely to experience severe outcomes from common infections, particularly those affecting the respiratory system.”

Pathogens such as influenza, pneumococcus, respiratory syncytial virus (RSV), and SARS-CoV-2 (COVID-19) are of particular concern. These diseases are associated with increased hospitalisation, complications, and mortality in older populations.

A/Prof Tate says infectious diseases in this demographic are not only acutely dangerous but can also lead to long-term health consequences.

“For example, influenza has been linked to higher risk of cardiovascular and neurovascular events, including myocardial infarction and stroke, following infection,” she said.

“These secondary effects further compound the health and economic burden on individuals, carers and the broader health system.”

The groups at most risk

Older Australians and parents of young children are especially urged to get vaccinated to protect themselves and their loved ones.

“The Immunisation Coalition’s latest national survey reveals that fewer Australians are choosing to protect themselves through vaccination,” A/Prof Tate said. “This raises concerns about the country’s preparedness for future flu seasons and highlights a growing public perception that influenza is not a serious disease.”

2025 Flu FAQs

Who should get the flu vaccination?

This year’s vaccine targets two strains of Influenza A and two of Influenza B. It is provided for free to these priority or higher risk groups

• People over 65 years old
• Children aged six months to five years
• People with serious health conditions
• People who are pregnant
• All Aboriginal people aged more than six months.

People outside these priority groups can also develop serious flu infections, so annual vaccination protects you, your family, workmates, and vulnerable groups. Vaccinated people are about 40-60 per cent less likely to get severe influenza – the rate depends on how far the virus has mutated from the vaccine. If the vaccine doesn’t completely prevent the flu, it may lessen the severity.

When is the best time to be vaccinated?

A flu vaccination takes up to four weeks to work, it starts to wear off after six months. The peak of the flu season is June to August, making the optimum time to get vaccinated around April, but anytime during flu season is a good time to receive the vaccine.

How does the flu vaccine work?

When you get a virus, your immune system builds a defence by making antibodies. If you encounter that virus again, those antibodies recognise the virus and know how to protect you from getting sick. The influenza vaccine contains proteins from the most recent flu virus and triggers your immune system to build an antibody protection. If you are exposed to that virus – your immune system recognises it and knows how to protect you. Every year, flu viruses mutate or change, so having the flu one year doesn’t protect you from getting it in the future.

Is the flu vaccine safe?

The vaccine does not contain live viruses and cannot cause influenza. It has a solid safety record, having been used around the world for many decades.

Does the flu vaccine have side effects?

The flu vaccine is made up of fragments of the virus, so it can’t cause the flu itself, but side effects include soreness and swelling where the shot was given. The immune response that is induced by the vaccine can cause low-grade flu-like symptoms which will resolve after one or two days. View here the reported side effects so far this year.

Can flu vaccines be given with other vaccines?

Yes. You can get the influenza vaccine at the same time as COVID-19, respiratory syncytial virus (RSV), pneumococcal and diphtheria vaccines.  This has been shown to be safe and produce a good immune response against both viruses.

I had the flu vaccination last year: do I need it again this year?

There are three good reasons why you should be vaccinated against flu every year:

1. The influenza vaccine changes every year – in response to the expected flu virus.
2. Your protection is most effective for three to four months after getting vaccinated and lasts about six months.   
3. If a person had a flu vaccine in late 2023 or early 2024, they are still recommended to receive a 2024 formulation of flu vaccine, which is generally available from April each year.

The highest level of protection occurs in the first three to four months after vaccination. Your protection then declines rapidly, so it’s important to receive the latest vaccine every year.  Flu viruses also mutate or change quickly, so having flu one year doesn’t always protect you from getting it in future.

What are flu symptoms?

Flu symptoms usually start with a runny nose, sneezing and a sore throat, like a cold. However, if you have the flu, it quickly and moves into headaches, fever or chills, aching muscles and joints, cough, shortness of breath, fatigue, and weakness. In some cases, vomiting and diarrhoea can occur in children.

Is it the flu or a cold?

Symptoms	Flu	Cold
Nausea, vomiting and diarrhea	More common in children	Uncommon
High temperature	Yes – for several days	Uncommon
Sweats	Moderate to severe	Mild
Aches	Moderate to severe	Mild
Cough and sore throat	Common	Common
Headache	Common	Mild
Stuffy or running nose	Yes – for several days	Passes in a few days
Fatigue	Common	Mild to moderate
Difficulty breathing, rapid breathing	More common in individuals with lung disease	More common in individuals with lung disease
Loss of appetite	Common	Mild

How is the flu diagnosed?

There is a pathology test for influenza, COVID-19, the common cold virus RSV and 14 other respiratory viruses.

There are also now Rapid Antigen Tests for influenza A and B, COVID-19 and RSV available at chemists and supermarkets. The results allow you to act quickly to purchase anti-viral medication that could shorten the length and severity of the flu or COVID-19.  It will also show whether children have a cold or a potentially deadly infection that could see them admitted to hospital.

I think I’ve got the flu …

Contact your doctor as soon as possible. Anti-viral drugs can make the infection milder, however they need to be taken as soon as you develop symptoms to be effective. If you experience severe symptoms or have other medical conditions, see a doctor or go to hospital. 

Just like COVID-19, stay at home and limit contact with family members and others as much as possible to reduce the spread of the virus. Wear a mask when around others, cover your mouth when you sneeze and throw out used tissues. Clean and disinfect the surfaces you touch. 

When is the flu contagious?

Anytime from a day before symptoms appear to about a week later. The first three days are the most contagious. Children and people with weakened immune systems may be contagious longer.

How do I prevent the flu?

The flu spreads easily; it can affect a large group of people in a very short time. It spreads through respiratory droplets created when an infected person sneezes, coughs or talks. You can also catch it by touching a surface where the virus has been left e.g. a door handle. 

Six ways to avoid catching or passing on the flu

1. Get a flu vaccine every year
2. Try not to touch your eyes, nose or mouth – this is usually how the virus gets into your body
3. Wash your hands regularly with soap and warm water
4. Sneeze or cough into a tissue and throw it in the bin
5. Clean and disinfect surfaces if someone at home is sick
6. If you have the flu – stay at home to avoid passing it on.

How long does the flu last?

From two to seven days but it can be as long as a couple of weeks. Symptoms are worst for the first three days. A cough and general fatigue may continue after other symptoms have gone.

What is the best way to recover?

For a healthy adult, your immune system will usually clear the flu virus. For the best chance of recovery, stay at home and rest. Treatments that may help you feel better include

• Drinking plenty of water
• Throat lozenges and saline nasal drops can help ease nose and throat symptoms
• Paracetamol and/or ibuprofen can lower your temperature and ease aches and pains.

See a doctor if symptoms change or become worse.

Flu complications

The most common complication is a secondary chest infection caused by bacteria. This can develop into pneumonia. A bacterial infection can be life-threatening, but, if treated early by antibiotics, can be cured. Symptoms of a secondary chest infection include

• Recurrence of a high temperature
• Worsening cough
• Shortness of breath, difficulty breathing
• Chest pain
• Ear infection
• Seizures.

Why do people die from the flu?

By the time patients with severe flu are admitted to hospital there are no effective drugs available to reduce the response the virus. My influenza research is focused on finding a treatment to save these lives. Currently the best protection from severe or life-threatening flu is annual vaccination at the start of the flu season.

When to seek medical help

Most people will recover from the flu, but you should always seek medical help if

• You are in an at-risk group; complications are more likely in the at-risk groups
• Your symptoms don’t improve, change or get worse.

Why are some years worse for the flu than others?

The influenza virus changes from year to year. There are two types of influenza, A and B, and each affects people differently, e.g. some affect children more than older people and vice-versa. Some of the following factors can make a flu season turn from good to bad:

• The flu variants that are circulating and changes to the virus during the season
• Susceptibility of the population to the virus circulating
• The uptake of the flu vaccine
• If the viruses that circulate differ from what was predicted and included in the vaccine.