How severe is this flu season shaping up to be?

Australia has recorded an increased number of lab-confirmed influenza cases in all jurisdictions early in 2025, but we can’t currently predict the severity of the upcoming season in Australia according to Professor Patrick Reading, Director of the WHO Collaborating Centre for Reference and Research on Influenza.

Professor Reading was joined by Professor Paul Griffin, Director of Infectious Diseases at Mater Health Services in Brisbane and Associate Professor of Medicine at the University of Queensland Medical School, and Professor Julie Leask, Professor of Public Health and Social Scientist, University of Sydney and Visiting Professorial Fellow at the National Centre for Immunisation Research and Surveillance at a media briefing hosted by the Australian Science Media Centre on Tuesday, 6 May to share the latest insights on the upcoming 2025 influenza season in Australia.

Professor Reading said that while the increased cases at this time of year is considered unusual compared to previous years, it highlights just how unpredictable the flu can be.

He explained that while some seasons have started early and others late, there have been irregularities in infection patterns since the COVID-19 pandemic.

“Despite the increased influenza activity, we can’t currently predict the severity of the upcoming season in Australia” said Professor Reading.

“This will be dependent on a range of factors; which virus subtype becomes dominant or which strain becomes dominant.”

As case numbers increase going into winter, experts will gain a better understanding of the dominant strains.

He added that these early infections may not be as a result of changes to the influenza virus, but could be influenced by human behavioural changes such increased travel from the Northern Hemisphere and declining vaccination rates.

Reflecting on the Northern Hemisphere experience, countries like the US had a severe season dominated H3N2 viruses, while areas like Europe or China experienced a milder season dominated by H1N1 viruses.

To address the problematic H3N2 strain, the vaccine has been updated for the upcoming flu season in the Southern Hemisphere to provide a better match against the circulating strains.

The WHO Global Influenza Surveillance and Response System monitors circulating virus strains worldwide and convenes biannual meetings to recommend candidate vaccine viruses for the upcoming flu seasons in each hemisphere. Working as part of this network, the WHO Collaborating Centre for Reference and Research on Influenza at the Doherty Institute collects samples of human influenza viruses within the southern hemisphere, and provides analysis for epidemiological, antigenic (immune response) and genetic characteristics.

Professor Paul Griffin highlighted the severity of influenza compared to other viral respiratory infections and discussed the best preventative and treatment measures.

“We hear this a lot; it’s just the flu, but it’s not just the flu. It’s a very severe viral infection in its own right and can be life-threatening,” he said.

Preparedness is crucial, with vaccination being a key measure, along with good hand hygiene, focus on air quality/ventilation, and avoiding contact with those who are unwell.

Presenting the findings from the Vaccination Insight Project, Professor Julie Leask reported on the perpetually low vaccination rates.

Survey results showed the biggest barrier to vaccination was cost. Additional barriers included making an appointment, inconvenient opening times, and inability to take time off work.

Professor Leask emphasised the importance of understanding these barriers to help governments develop effective solutions, highlighting an opportunity to revise vaccination campaigns.

“It’s always a bad flu season because it’s hospitalising and killing people and making them sick…it doesn’t necessarily need to be a record flu season for it to be important,” said Professor Leask.

Watch the expert briefing via the recording below. For a full briefing including the media Q&A session visit the Scimex website.