"Sharp rise" in flu cases in the US could indicate potential impact on Australia

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Experts are warning a severe flu season is likely this year as the Northern Hemisphere braces for a surge in infections.

According to the National Notifiable Disease Surveillance System, there were 1,055 confirmed influenza cases in Australia in the first week of 2025.

However, flu cases typically peak in winter when the virus can survive longer outside the body, and people spend more time gathering in enclosed spaces.

Australia’s worsening flu seasons

Australia has reported almost 888,000 confirmed cases of influenza since 2022, after infections took a dip during the height of the COVID-19 pandemic when Australia’s international borders were closed.

There were just 750 recorded infections in 2021 and 21,343 in 2020, a significant drop from the 313,453 reported in 2019 — the year before the pandemic began.

The 2019 figure was the highest annual total since data collection began in 2001, but was eclipsed in 2024 when 364,000 influenza cases were confirmed.

A graph shows confirmed influenza cases in Australia over the years.

Australia has reported at least 888,000 confirmed cases of influenza since 2021. Source: SBS News

Decline in vaccination rates

Influenza cases, as expected, increased after Australia’s international borders reopened. But the infection record in 2024 also came as vaccination rates declined.

In 2020, the influenza vaccination coverage rate for those aged over 65 was 61.9 per cent, which has since slipped to 60.5 per cent in 2024.

For those aged 50 to 65, the coverage rate dropped by 2.5 percentage points 32.7 per cent over the same period.

Vaccination coverage among the largest age group — 15 to 50-year-olds — also fell 3 percentage points to 20.4 per cent over the past four years.

And it was 14 per cent for children aged 5 to 15 in 2024, down from 27.4 per cent in 2020.

‘Vaccine fatigue’ and misinformation

Some health experts are concerned the public may feel burnt out by the annual reminders to get vaccinated, a factor that could be contributing to the decline in immunisation rates.

Andrew Bartlett, a lecturer in pharmacy practice at the University of Sydney, told SBS News that “vaccine fatigue” could be a significant contributor.

“Our vaccination rates have been lower, some suggestions about vaccination fatigue may be significant, and increasing vaccination rates is essential if we want to reduce the spread of the disease,” he said.

Matthew Mason, a health researcher at the University of the Sunshine Coast, pointed to the growing impact of misinformation, which he believes is contributing to a “growing distrust of vaccinations” across Australia.

“We’re seeing lowering of vaccination rates across a whole range of vaccines in Australia, following on from the misinformation and the campaigns around the COVID-19 vaccination,” he said.

Predicting a severe flu season for winter 2025

Bartlett said winter factors, such as colder temperatures and reduced sunlight, could exacerbate the spread of the flu, compounding the challenges posed by declining vaccination rates.

“Another theory suggests our immune system may be slightly lower due to lower vitamin D from a lack of sunlight. Another important factor is that the vaccine from the previous year is probably wearing off, making the vaccinated person more susceptible,” he said.

Bartlett said overseas influenza cases can offer insight into what may unfold in Australia.

“The Northern Hemisphere is generally a fairly good indicator of what we can expect. It gives us an idea of both the amount of virus circulating as well as the dominant strains.”

Severe 2025 flu season likely, prompting calls to get vaccinated image

One country that experts are closely monitoring is the United States.

Paul Van Buynder, a professor in the School of Medicine at Griffith University, said there has been a “dramatic increase” in influenza cases in some states in the US.

“What we do know is at the moment in the United States, and some parts of the Northern Hemisphere, influenza rates are starting to dramatically increase,” he said.

“We’re expecting that they’ll see a fairly severe season in the Northern Hemisphere, and that usually portends to us getting a fair amount of flu in the next year as well.”

The US Centers for Disease Control and Prevention (CDC) recently reported an 18.7 per cent increase in influenza cases compared to the previous week, ending 21 December 2024.

The CDC estimates there have been at least 5.3 million illnesses, 63,000 hospitalisations, and 2,700 flu-related deaths so far this season in the US.

How much is the flu vaccine in Australia?

The influenza vaccine is free for at-risk Australians, including children six months to under five years, pregnant women and people aged 65 and over.

For others, pharmacies across Australia charge around $25 for a flu jab.

In Queensland, the government will continue its funding of a free influenza vaccine program for all Queenslanders aged 6 months and over in 2025.

Mason suggested offering free vaccinations to people outside the at-risk groups could help encourage more people to get the jab.

“The people who are heading out to work, the kids who are going out to school and going into shopping centres and those sorts of places, they’re the ones that will help spread any illness,” he said.

If we can vaccinate those [groups], we reduce the risk of other people getting unwell in the community.”