The 2025 Australian influenza season peaked between June and July, much earlier than the historical average. Its early onset, rapid growth, and widespread community transmission make this year’s wave one of the most severe in recent history. Additionally, according to data from the Australian Respiratory Surveillance Report, influenza, Respiratory Syncytial Virus (RSV), and SARS-CoV-2 are co-circulating at high levels, creating what experts call a “tripledemic” scenario, increasing hospitalizations and stressing the healthcare system. For public health authorities and professionals across Europe, tracking these trends in Australia’s flu season is more than just observation, but it’s a way to predict and prepare for the upcoming autumn-winter respiratory season. This article reviews the latest Australian surveillance data to forecast the severity, timing, and dominant viruses of the upcoming 2025–2026 European flu season, helping Europe use Australia’s experience to prepare for what could be a high-burden influenza season and reduce the expected surge in flu cases, hospitalizations, and deaths.
Australia, Europe’s early warning system
Due to its opposite seasonal cycle, similar circulating strains, vaccine formulations, demographic vulnerabilities, and strong national surveillance infrastructure, Australia serves as a sentinel for the Northern Hemisphere’s upcoming flu season, indicating what Europe and North America will face in their fall and winter months. Notably, even the WHO Global Influenza Program relies on Southern Hemisphere data to help determine the composition of the Northern Hemisphere vaccine.
This year, activity began rising sharply in May, and according to the Australian Respiratory Surveillance Report, influenza-like infection consultation rates in general practice sentinel networks have surpassed the five-year average, signaling high community transmission. These patterns have historically preceded intense flu seasons in Europe.
The good news is that genomic surveillance confirms the 2025 Southern Hemisphere strains are antigenically comparable to circulating ones, implying that vaccine effectiveness should be strong. However, case numbers remain high, pointing to suboptimal vaccination coverage as a key driver of transmission. For European health systems, this means that even with an optimally matched vaccine, low vaccination rates will continue to cause transmission, hospitalizations, and Intensive Care Unit (ICU) admissions.
Australia’s flu season 2025 in numbers
The current rate of respiratory infections is the highest since 2019, surpassing levels seen in 2023 and 2024. This resurgence indicates a post-pandemic return to pre-COVID-19 circulation patterns, with increased population vulnerability due to waning immunity and reduced non-pharmaceutical interventions. The 2025 flu season in Australia has been characterized by both volume and speed:
- Between May and June 2025, monthly flu cases more than doubled in most Australian regions.
- Over 150,000 laboratory-confirmed influenza cases have been reported since the beginning of 2025, according to the Royal Australian College of General Practitioners.
- Hospitalizations for severe acute respiratory infections reached 7,641 admissions by mid-July, including 3,081 due to influenza—the highest among all respiratory pathogens.
- Influenza was the second most common pathogen causing ICU admissions for respiratory infections, behind only rhinovirus/enterovirus.
The demographic impact of this year’s season is also clear: children aged 0–9 have experienced the highest infection rates, while hospitalizations and severe outcomes are concentrated among adults over 65. This age difference highlights the dual burden of influenza—high transmission in younger populations and high severity in older adults.
Recently, influenza cases declined during the two-week period of July 14–27, suggesting the peak might have passed. However, RSV remains elevated compared to previous years—50% higher than 2024 levels—and COVID-19 still significantly contributes to ICU admissions, indicating ongoing circulation of these respiratory viruses.
Flu, RSV, and COVID-19: the 2025 “tripledemic”
As anticipated in the previous chapter, the 2025 season is not driven by influenza alone. Instead, the season exemplifies the post-pandemic reality of co-circulating respiratory pathogens such as Influenza, RSV, and SARS-CoV-2, in a scenario now commonly referred to as the “tripledemic.” Data from the Short Period Incidence Study of Severe Acute Respiratory Infection shows that 4.4% of patients had co-detections of multiple pathogens, which increases clinical complexity and resource use.
Additional pathogens such as human metapneumovirus, rhinovirus, and Bordetella pertussis have also contributed to the disease burden, especially in pediatric ICU cases. These agents, although less common, can prolong illness and mimic influenza, leading to diagnostic delays.
These findings highlight the need for integrated surveillance systems capable of tracking multiple pathogens simultaneously and providing real-time information for public health responses.
Europe’s winter forecast
By analyzing Australia’s 2025 flu season, epidemiologists forecast a high-burden, early, and potentially severe flu season for Europe in 2025–2026.
- Early and Intense Season: The early peak in Australia often correlates with earlier and more intense seasons in the Northern Hemisphere. The European flu season is expected to begin from late October to mid-November 2025, with a peak between late December 2025 and January 2026. The season is projected to end around March to April 2026, with possible residual circulation into May.
- Co-Circulation of Pathogens: The triple threat of influenza, RSV, and SARS-CoV-2 is expected to persist in Europe as it does in Australia.
- High Burden: Based on Australia’s experience and assuming current vaccination rates, Europe could see an estimated 125-215 million total respiratory cases during the 2025–2026 season, affecting 15–25% of the population.
The dominant strains are expected to be similar to those in Australia: influenza A H1N1 and H3N2, and B/Victoria. However, the severity of the season will depend on other factors—particularly vaccination coverage and public awareness, which could pose a significant risk for uncontrolled spread.
Age, vaccination, and health gaps: who is most at risk?
The connection between low vaccination rates and high disease burden is undeniable: the least protected are the most vulnerable. Despite the availability of seasonal flu vaccines, only 29.5% of the Australian population had received a flu shot by late July 2025. Of note, 90% of hospitalized flu patients are unvaccinated.
Adults over 65 account for 50% of influenza hospitalizations, while children, though less likely to be hospitalized, play a key role in transmission. School-based outbreaks can spark community-wide spread, making pediatric vaccination a key part of herd immunity. Immunocompromised patients and patients with comorbidities are at higher risk of severe outcomes but are often excluded from routine surveillance. Mortality data from the Australian Bureau of Statistics show that deaths linked to influenza, RSV, and COVID-19 remain elevated compared to pre-pandemic levels. Among ICU admissions, the in-hospital mortality rates are 9.4% for influenza, 16.6% for COVID-19, and 6.0% for RSV.
These figures highlight the ongoing lethality of respiratory pathogens, especially among vulnerable populations. Clearly, disparities in healthcare systems worsen the risk. Rural and underserved communities frequently face limited access to vaccines, testing, and care, leading to delayed treatment and worse outcomes.
In Europe, similar trends can be seen, with flu vaccination coverage among older adults remaining alarmingly low, ranging from 57–60% in Italy and 10–25% in Eastern Europe—far below the WHO’s recommended 75% target for high-risk groups. The consequences are clear: increased hospitalizations, ICU admissions, and preventable deaths. That’s why European public health messaging must focus on active engagement, utilizing trusted community leaders, digital platforms, and workplace programs to boost vaccination rates.
Emerging threats & surveillance needs
In addition to seasonal influenza, new and re-emerging pathogens demand vigilance. First, Australia reported outbreaks of highly pathogenic avian influenza H7N8 in Victoria and is currently monitoring a few cases of H5N1. While human cases have not been reported, respiratory symptoms in patients exposed to poultry must be documented and thoroughly evaluated. These zoonotic threats serve as a reminder to healthcare professionals of what happened just five years ago with COVID-19 and emphasize the importance of a strong One Health approach—integrating human, animal, and environmental monitoring—when addressing these diseases.
Second, SARS-CoV-2 continues to evolve. For instance, the XFG sub-lineage (designated as a Variant Under Monitoring by WHO in June 2025) requires genomic tracking to assess immune escape and transmissibility. Updated COVID-19 boosters targeting this variant are expected to be available in Europe by fall 2025.
Regarding healthcare system needs, strengthening national influenza surveillance networks and reference laboratories is essential for quick data sharing, accurate burden assessment, and rapid response. This includes validated sample collection systems, multiplex PCR platforms, next-generation sequencing (NGS), and automated sample processing tools. Incorporating these diagnostic solutions into laboratory workflows will improve efficiency and data quality.
Five ways Europe can prepare
- Monitor Australia’s Surveillance Data. Monitoring Australian and WHO reports in real-time will help assess strain dominance, clinical severity, and adjust forecasts.
- Strengthen Integrated Surveillance. Expand national and international systems to track flu, RSV, COVID-19, and emerging pathogens using standardized case definitions and data sharing protocols through platforms like the European Centre for Disease Prevention and Control (ECDC). This will be crucial for real-time monitoring and a coordinated response.
- Promote Vaccination Campaigns. Targeted, culturally sensitive campaigns can increase uptake among seniors, healthcare workers, and children. Prioritizing high-risk groups, expanding access points, and integrating vaccination into routine clinical workflows must also be considered.
- Prepare Healthcare Systems. Hospitals should anticipate increased admissions, especially in geriatric and pediatric units. Contingency plans for ICU capacity, staffing, and antiviral supply should be reviewed. Ensuring protective equipment and vaccinating healthcare workers may help mitigate transmission within healthcare facilities.
- Support Labs and Diagnostics Providers. Collaborate with laboratories to streamline testing workflows, validate platforms, and provide reliable collection and processing tools tailored to local needs.
Conclusions
The 2025 Australian influenza season serves as a crucial early warning for Europe: winter 2025–2026 may be one of the most challenging in years. With an estimated 150–215 million cases across EMEA, proactive measures are vital. The quick onset, high case numbers, and co-circulation of multiple respiratory pathogens highlight the need for proactive public health actions and clinical preparedness. Enhanced surveillance, timely diagnostic testing, and strong healthcare system planning will be essential to reduce the impact of Europe’s 2025–2026 respiratory season. Since vaccination remains the key prevention method, increasing coverage is essential. By learning from Australia’s experience, Europe can build more efficient healthcare systems and better protect its populations during the winter months.
Bibliography
- https://www.health.gov.au/resources/collections/australian-respiratory-surveillance-reports-2025
- https://www.who.int/teams/global-influenza-programme/surveillance-and-monitoring/influenza-updates/current-influenza-update
- https://www.theguardian.com/australia-news/2025/may/23/flu-record-cases-vaccination-australia
- https://www1.racgp.org.au/newsgp/clinical/worrying-signs-as-peak-flu-season-draws-near
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