A Surprising Shift: Flu Deaths Spike in 2025
In a surprising turn of events, the Australia Bureau of Statistics (ABS) has revealed that 2025 witnessed the highest number of flu-related deaths this century. This revelation challenges our understanding of respiratory infections and prompts us to delve deeper into the factors contributing to this unexpected trend.
The ABS's latest report highlights a significant shift in mortality patterns. Since August 2025, influenza-related deaths have surpassed those attributed to COVID-19, a stark contrast to previous years. The bureau's data, released on Tuesday, paints a clear picture of this shift.
Last year, Australia recorded approximately 2,161 COVID-19 deaths and 1,701 influenza deaths. Additionally, there were around 582 deaths associated with RSV, a notable increase from the previous year.
Epidemiologist Catherine Bennett attributes this rise to the emergence of a new flu variant, H3N2, known as Subclade K. "We witnessed the highest rates in a long time, persisting through December and into January," Professor Bennett explained.
The Summer Flu Peak: A Rare Phenomenon
Traditionally, the coronavirus has been the leading cause of acute respiratory infection deaths between 2023 and 2025. However, a significant decline in COVID-19 deaths was observed last year, with the number dropping by more than half. In 2024, 5,108 people succumbed to COVID-19, compared to 2,161 in 2025.
According to the ABS, there has been a pattern of two mortality peaks surrounding COVID-19 since late 2021. One peak occurs between November and January, while the other emerges between May and August. Interestingly, during the summer peak in 2025, influenza deaths outnumbered COVID-19 deaths, with approximately 741 flu-related deaths compared to 428 COVID-related deaths.
Professor Bennett from Deakin University attributes this summer flu peak to the Subclade K strain, which extended the flu season into the warmer months. She emphasizes that this variant differs from other H3N2 strains, explaining, "The Hemagglutinin protein had several unique mutations, making the vaccine less effective against this new virus. This led to more cases during our extended winter outbreak, resulting in an unusual summer wave of influenza."
COVID-19's Changing Impact
The ABS notes a shift in the severity of COVID-19 peaks, beginning in November 2024 and January 2025. When compared to October 2024, the number of deaths during this period was significantly lower than in previous years. Preliminary data suggests no summer peak in 2025-2026, but the ABS will continue monitoring as more death registrations are received.
Professor Bennett adds that COVID-19 is becoming a seasonal virus, primarily impacting winter months. "Winter remains a critical period for COVID-19, causing more deaths than influenza. However, for the first time, COVID-19 had a reduced impact on summer deaths."
The Unpredictability of Summer Flu Waves
Professor Bennett highlights that summer flu waves are not a consistent annual occurrence. She cites 2017, which recorded approximately 1,656 influenza deaths, as an example of a year with a notable summer rise. "It doesn't mean influenza will consistently cause summer waves. This year's numbers resemble those of 2017, one of our worst years on record."
She emphasizes that a combination of factors contributed to this year's summer flu wave, including lower vaccination rates, leaving more people vulnerable. "Combined with the extended winter wave, particularly with the new subvariant influenza, this year has been particularly challenging for respiratory diseases."
The Importance of Vaccination
Professor Bennett stresses the importance of increasing vaccination rates, especially for those over 70, who are most vulnerable. The majority of deaths related to COVID-19, RSV, and influenza occurred in this age group. She expresses concern that only about 60% of people over 65 are covered by the flu vaccine.
"There are still many unvaccinated individuals, including those vulnerable to severe disease, which could be a cause of death. Vaccines may not prevent infection but can reduce disease severity and the likelihood of death."
This unexpected shift in mortality patterns highlights the need for ongoing public health measures and vaccination campaigns to mitigate the impact of respiratory infections.
