Surveillance for severe influenza, COVID-19, and RSV in patients admitted to sentinel Australian hospitals in 2025: the Influenza Complications Alert Network (FluCAN) and the Paediatric Active Enhanced Disease Surveillance (PAEDS) system.
Influenza, coronavirus disease 2019 (COVID-19) and respiratory syncytial virus (RSV) are common acute respiratory infections and are a cause of significant morbidity and mortality. This report summarises the epidemiology of hospitalisations with laboratory-confirmed influenza, COVID-19 and RSV in 2025 in an Australian sentinel surveillance system.
The Influenza Complications Alert Network (FluCAN) and the Paediatric Active Enhanced Disease Surveillance (PAEDS) are collaborative sentinel hospital-based surveillance programs that operate at 23 sites across all jurisdictions in Australia. Influenza, COVID-19 and RSV patients were defined as those hospitalised due to an acute respiratory infection at the sentinel hospitals with virus confirmation by nucleic acid detection.
In 2025, there were 8,749 hospitalisations of patients with influenza; 3,501 with COVID-19; and 5,105 with RSV reported at the 23 sentinel hospitals. Of patients hospitalised with influenza, 4,397 (50.3%) were children (< 16 years of age); 697 (8.0%) were Aboriginal and/or Torres Strait Islander people; and 5,020 (57.4%) had chronic comorbidities. The mean length of hospital stay for patients with influenza was 4.4 days (median: 2 days). Influenza hospital admissions peaked nationally in epidemiological week 28. Influenza vaccine effectiveness against hospitalisation with any influenza type/subtype was estimated at 43% (95% confidence interval [95% CI]: 39-48%) and was highest for influenza B (75% [95% CI: 69-80%]), and lowest for influenza A H3N2 including subclade K (30.5% [95% CI: 15.0-43.2%]). Of patients hospitalised with COVID-19, 1,057 (30.2%) were children (< 16 years of age); 230 (6.6%) were Aboriginal and/or Torres Strait Islander people; and 2,544 (72.7%) had chronic comorbidities. The mean length of hospital stay for patients with COVID-19 was 7 days (median: 3 days). COVID-19 hospital admissions peaked nationally in week 26. In adults ≥ 75 years of age, the relative risk of hospitalisation was 40% (95% CI: 25-52%) lower in those who had received a COVID-19 vaccine within 180 days, compared to those vaccinated > 1 year prior to admission. Of patients hospitalised with RSV, 1,551 (30.4%) were infants (< 1 year of age) and 3,723 (72.9%) were young children (< 5 years of age); 348 (6.8%) were Aboriginal and/or Torres Strait Islander people; and 2,110 (41.3%) had chronic comorbidities. The mean length of hospital stay for patients with RSV was 3.5 days (median: 2 days). There was a peak in activity in week 28.
Since 2022, influenza, RSV and COVID-19 have co-circulated. In 2025, disease severity-as indicated by average length of stay and proportions admitted to intensive care-was similar in patients hospitalised with any of the three pathogens. Assessment of vaccine effectiveness demonstrated protection against influenza hospitalisation and short-term protection against hospitalisation with COVID-19 in older people.
The Influenza Complications Alert Network (FluCAN) and the Paediatric Active Enhanced Disease Surveillance (PAEDS) are collaborative sentinel hospital-based surveillance programs that operate at 23 sites across all jurisdictions in Australia. Influenza, COVID-19 and RSV patients were defined as those hospitalised due to an acute respiratory infection at the sentinel hospitals with virus confirmation by nucleic acid detection.
In 2025, there were 8,749 hospitalisations of patients with influenza; 3,501 with COVID-19; and 5,105 with RSV reported at the 23 sentinel hospitals. Of patients hospitalised with influenza, 4,397 (50.3%) were children (< 16 years of age); 697 (8.0%) were Aboriginal and/or Torres Strait Islander people; and 5,020 (57.4%) had chronic comorbidities. The mean length of hospital stay for patients with influenza was 4.4 days (median: 2 days). Influenza hospital admissions peaked nationally in epidemiological week 28. Influenza vaccine effectiveness against hospitalisation with any influenza type/subtype was estimated at 43% (95% confidence interval [95% CI]: 39-48%) and was highest for influenza B (75% [95% CI: 69-80%]), and lowest for influenza A H3N2 including subclade K (30.5% [95% CI: 15.0-43.2%]). Of patients hospitalised with COVID-19, 1,057 (30.2%) were children (< 16 years of age); 230 (6.6%) were Aboriginal and/or Torres Strait Islander people; and 2,544 (72.7%) had chronic comorbidities. The mean length of hospital stay for patients with COVID-19 was 7 days (median: 3 days). COVID-19 hospital admissions peaked nationally in week 26. In adults ≥ 75 years of age, the relative risk of hospitalisation was 40% (95% CI: 25-52%) lower in those who had received a COVID-19 vaccine within 180 days, compared to those vaccinated > 1 year prior to admission. Of patients hospitalised with RSV, 1,551 (30.4%) were infants (< 1 year of age) and 3,723 (72.9%) were young children (< 5 years of age); 348 (6.8%) were Aboriginal and/or Torres Strait Islander people; and 2,110 (41.3%) had chronic comorbidities. The mean length of hospital stay for patients with RSV was 3.5 days (median: 2 days). There was a peak in activity in week 28.
Since 2022, influenza, RSV and COVID-19 have co-circulated. In 2025, disease severity-as indicated by average length of stay and proportions admitted to intensive care-was similar in patients hospitalised with any of the three pathogens. Assessment of vaccine effectiveness demonstrated protection against influenza hospitalisation and short-term protection against hospitalisation with COVID-19 in older people.
Authors
Morgan Morgan, Dwyer Dwyer, Holmes Holmes, Irving Irving, Rees Rees, Vincent Vincent, Chiong Chiong, Marr Marr, Korman Korman, Bartolo Bartolo, Cooley Cooley, Bowler Bowler, Kok Kok, Runnegar Runnegar, Fatovich Fatovich, Waterer Waterer, Macartney Macartney, Crawford Crawford, Bellamy Bellamy, Carr Carr, Marshall Marshall, Clark Clark, Francis Francis, McMullan McMullan, Britton Britton, Wood Wood, Kotsimbos Kotsimbos, Kelly Kelly, Blyth Blyth, Cheng Cheng
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