2024 expert flu season guide

Influenza (flu) is a potentially fatal disease. Last year 3,696 Australians were admitted to hospital with influenza and there were 379 flu deaths. The highest number of hospitalisations was in infants and children, mostly likely due to lower vaccination rates in this group.

Hudson Institute’s viral infection scientist, Associate Professor Michelle Tate, helps you and your family prepare for and stay well in the 2024 flu season.

When is Australia’s flu season like?

Traditionally, flu season has run from April to October with a peak in August. However, since 2022, the flu season started earlier in March and peaked in June.

Is this a bad year for flu?

Let’s compare current flu numbers to last year’s

• Up until the end of May, there were 72,469 flu notifications. This is more than the same period in 2023, which had 66,073 notifications.
• Last year’s flu season was characterised by an earlier than usual peak in May and an overall longer duration.

Based on these figures, this flu season could be about roughly equal to or above last year’s numbers.

Influenza can be both mild and fatal

While influenza can be mild, it can also cause serious illness in otherwise healthy people of all ages, leading to hospitalisation and sometimes even death. Here’s the 2023 flu season numbers summary, showing who was most affected.

• 252,296 reported flu cases. Overall case numbers were likely much higher.
• 376 influenza-associated deaths.
• There were 3,696 hospital admissions, 256 of those were admitted to ICU.
  • 72 per cent were children aged less than 16 years
  • 17 per cent were adults aged 16-64 years
  • 11 per cent were adults aged 65 years.
• 39 deaths in admitted patients with influenza, nine were children aged less than 16 years.

Who is most a risk?

Infants, children, the elderly and people with chronic illnesses or suppressed immune systems are most at risk.

Who was most affected last year?

1. Children aged five to nine years had the highest flu notification rates, followed by newborns to four year-old children.
2. There was a marked drop in vaccination for infants and children. Compared with 2022 vaccinations dropped by
   • 70 per cent for babies and toddlers, six months to four years
   • 64 per cent for five to 14 year-olds
   • 16 per cent across Australia.

Flu can be severe for infants and children – it can overwhelm a young immune system. Vaccination is the best protection from the flu for everyone, including infants and children.

Who should get the flu shot?

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

• Children aged six months to five years
• People over 65 years old
• 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 get the flu shot?

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.

Is the flu vaccine safe?

The vaccine has been around for many decades and has a safety record. It does not contain live influenza viruses and cannot cause influenza.

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.

Does the flu vaccine have side effects?

There is no live virus in the flu vaccine. It is made up of fragments of the virus, so it can’t cause the flu itself. However, 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 to two days.

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 in 2023, do I need it in 2024?

Yes, for three reasons

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 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 diarrhea 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. 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 see 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 factors that make a flu season turn from good to bad

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

Why did the flu season starting earlier this year?

Flu cases and vaccinations declined during the pandemic, because of COVID-19-related restrictions. However, there is now lower immunity and increased susceptibility to the flu. Vaccination prevents a severe response to the flu and reduces transmission in schools and communities.

Why do we get flu in winter?

Flu cases are reported all year but are more common during winter, which is why it’s called the flu season. It is believed there is a ‘flu season’ because in winter people spend more time indoors and in close contact with each other.