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

Authors

  • Dr Hannah J Morgan Epidemiology Research Fellow, Monash Health and School of Clinical Sciences, Monash University
  • Prof. Dominic E Dwyer Clinical Professor, University of Sydney and Westmead Hospital
  • Prof. Mark Holmes Professor, Adelaide University; Respiratory and Sleep Medicine Specialist, Royal Adelaide Hospital
  • Prof. Louis Irving none@example.com
  • A/Prof. Megan Rees Head of Unit for Respiratory Medicine and Sleep Disorders, Royal Melbourne Hospital and University of Melbourne
  • Dr Stephen Vincent Respiratory Physician, Cairns Base Hospital
  • Dr Fabian Chiong Infectious Diseases Physician, Department of Infectious Diseases, Canberra Health Services and Australian National University
  • Dr Ian Marr Head of Infectious Diseases, Canberra Health Services and Australian National University
  • Prof. Tony M Korman Adjunct Clinical Professor, Monash University Monash University and Monash Health
  • Dr Caroline Bartolo Infectious Disease Physician, University Hospital Geelong, Barwon Health and Deakin University
  • A/Prof. Louise Cooley Director of Microbiology, Royal Hobart Hospital
  • A/Prof. Simon Bowler Associate Professor, Mater Health
  • Dr Jen Kok Medical Virologist, Centre for Infectious Diseases and Microbiology Laboratory Services, NSW Health Pathology-Institute of Clinical Pathology and Medical Research, Westmead Hospital
  • Dr Naomi Runnegar Infectious Diseases Physician and Clinical Microbiologist, Princess Alexandra Hospital
  • Prof. Daniel M Fatovich Professor of Emergency Medicine, University of Western Australia; Director of Research, East Metropolitan Health Service
  • Prof. Grant Waterer Professor of Medicine, University of Western Australia; Director of Clinical Services, Royal Perth Hospital
  • Prof. Kristine Macartney Director, National Centre for Immunisation Research and Surveillance (NCIRS) within Kids Research, Children’s Hospital at Westmead
  • Prof. Nigel Crawford Director of SAEFVIC, Murdoch Children's Research Institute; Head of Immunisation Service, Royal Children’s Hospital, Melbourne
  • Karen Bellamy Nurse Practitioner, Monash Health
  • Dr Jeremy Carr Head, Paediatric Infectious Diseases, Monash Health
  • Prof. Helen S Marshall Professor in Vaccinology, Adelaide University; Medical Director of VIRTU, Women’s and Children’s Health Network
  • A/Prof. Julia E Clark Director of Infection Management and Prevention, Queensland Children’s Hospital
  • Prof. Joshua R Francis Paediatric Infectious Disease Physician, Royal Darwin Hospital, Menzies School of Health Research, Charles Darwin University
  • A/Prof. Brendan McMullan Paediatric Infectious Disease Physician and Microbiologist, Sydney Children’s Hospital and University of New South Wales
  • A/Prof. Philip Britton Paediatric Infectious Diseases Physician, Children’s Hospital at Westmead and University of Sydney
  • Prof. Nicholas Wood Paediatric Infectious Diseases Physician, Children’s Hospital at Westmead and University of Sydney
  • A/Prof. Tom Kotsimbos Head of Respiratory Medicine Laboratory, Monash University; Specialist Respiratory and Transplant Physician, Alfred Hospital
  • Prof. Paul Kelly Founder and Principal, PK Public Health Advisory; Professor, College of Law, Governance and Policy, Australian National University
  • Prof. Christopher C Blyth Professor of Paediatrics, University of Western Australia, The Kids Research Institute Australia, Perth Children’s Hospital and PathWest Laboratory Medicine
  • Prof. Allen Cheng Program Director, Medical Specialties, Monash Health and Professor, School of Clinical Sciences and School of Public Health and Preventive Medicine, Monash University

DOI:

https://doi.org/10.33321/cdi.2026.50.058

Keywords:

influenza, public health surveillance, influenza vaccine, COVID-19 vaccine, vaccination coverage, coronavirus

Abstract

Introduction
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.

Methods
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.

Results
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.

Discussion
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.

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Published

29/09/26

How to Cite

Morgan, Hannah, Dominic Dwyer, Mark Holmes, Louis Irving, Megan Rees, Stephen Vincent, Fabian Chiong, et al. 2026. “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”. Communicable Diseases Intelligence 50 (September). https://doi.org/10.33321/cdi.2026.50.058.

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