Nirsevimab, a long-acting monoclonal antibody with activity against respiratory syncytial virus (RSV), was introduced into the Queensland paediatric RSV prevention program in 2024. Using Queensland Notifiable Conditions Register (NoCS) data, we found that the infant cohort eligible for the nirsevimab program had lower RSV hospitalisation rates than comparable pre-program cohorts. The population-level impact of nirsevimab was greatest during the first month of life (incidence rate ratio [IRR]: 0.22; 95% confidence interval [95% CI]: 0.16-0.31; representing a 78% reduction in hospitalisation rate), with its magnitude gradually declining thereafter until nine months of age (IRR: 0.77; 95% CI: 0.62-0.96; a 23% reduction), following which the impact of nirsevimab on hospitalisation rate, with increasing age of the infant or child, was no longer statistically significant. An interrupted time-series analysis demonstrated an immediate 63% reduction in RSV hospitalisations following nirsevimab's introduction (IRR: 0.37; 95% CI: 0.23-0.60), showing a substantial population-level impact of the program in Queensland, Australia.

This report from the Australian Rotavirus Surveillance Program (ARSP) describes the circulating rotavirus genotypes identified in children and adults during the period 1 January to 31 December 2025. In 2025, the ARSP saw a continuation of a high burden of rotavirus disease in the Australian population. During this period, 2,419 faecal specimens were referred to the National Rotavirus Reference Centre (NRRC) for rotavirus G- and P-genotype analysis; of these samples, 2,288 were confirmed as rotavirus positive. This represents the highest number of referred samples and the highest number of positive samples recorded in a single surveillance year in the NRRC's more than 20-year history. Of the 2,288 samples confirmed rotavirus positive, 2,071 (90.5%) were identified as wildtype rotavirus; 215 (9.4%) were identified as the Rotarix vaccine-like strain; and two G1P[8] samples could not be confirmed as wildtype or vaccine-like due to inadequate sequence quality. The equine-like G3P[8] variant was the dominant genotype nationally (87.7%; n = 1,816/2,071). Other genotypes were identified at low frequencies, including wildtype G1P[8] (0.3%; n = 6/2,071), G2P[4] (2.0%; n = 42/2,071), G3P[8] (2.4%; n = 50/2,071), G8P[8] (0.5%; n = 10/2,071), G9P[4] (0.3%; n = 6/2,071), G9P[8] (2.2%; n = 46/2,071) and G12P[8] (0.3%; n = 6/2,071). Genotype distribution was consistent nationally, with equine-like G3P[8] the dominant genotype in all jurisdictions. Consistent with observations in recent years, a small number of samples with unusual genotypes were identified (3.7%; n = 77/2,071). Of these unusual genotypes, the most frequently detected was equine-like G3P[6] which accounted for 26.0% of unusual samples (n = 20/74) and 1.0% of all positive wildtype samples (n = 20/2,071). The high number of rotavirus positive samples received by the program reflected the notifications for rotavirus disease reported to the National Notifiable Diseases Surveillance Service (NNDSS). Across Australia, 9,520 notifications were recorded, which is the second highest annual total reported since rotavirus became nationally notifiable in 2018. Outbreaks were reported in the Northern Territory, Western Australia and Queensland. The ability to monitor the genotypes of rotavirus strains causing disease across ages and jurisdictions provides important data to aid in assessing the performance of the national rotavirus vaccination program and to inform public health interventions during outbreaks. The ARSP also provides important data to monitor annual variations in genotypes circulating in the population. Understanding the diversity of genotypes in circulation and the emergence of variants provides important context for any changes observed in disease epidemiology in the community. The ARSP provides diagnostic laboratories with valuable feedback on laboratory data quality by reporting incidences of wildtype, vaccine-like, and/or false positive rotavirus results.

The Australian National Neisseria Network (NNN) comprises reference laboratories in each state and territory that report data on antimicrobial susceptibility testing to an agreed group of antimicrobial agents for the Australian Gonococcal Surveillance Programme (AGSP). The AGSP data are presented quarterly in tabulated form, as well as in the AGSP annual report. This report presents national gonococcal antimicrobial resistance surveillance data from 1 January to 31 March 2026.

The Australian Gonococcal Surveillance Programme (AGSP) has continuously monitored antimicrobial resistance in Neisseria gonorrhoeae (NG) for more than 45 years through the system of jurisdictional Neisseria reference laboratories, the National Neisseria Network (NNN). In 2025, a total of 10,204 isolates across Australia, from public and private sectors, were tested for in vitro antimicrobial susceptibility by standardised methods. In 2025, the AGSP captured antimicrobial susceptibility data for 23.9% of all gonococcal infection notifications nationally. The current treatment recommendation for gonorrhoea, for the majority of Australia, continues to be dual therapy with ceftriaxone and azithromycin. In 2025, of NG isolates tested, 0.73% (74/10,204) met the World Health Organization (WHO) criterion for decreased susceptibility (DS) to ceftriaxone, defined as a minimum inhibitory concentration (MIC) ≥ 0.125 mg/L. This proportion of isolates meeting the ceftriaxone DS criterion was greater than that reported in 2024 (0.51%), with the majority from New South Wales and Victoria. Genomic analysis indicated that 64.9% of these isolates (48/74) possessed the mosaic penA 60.001 allele, the key target associated with ceftriaxone resistance. Resistance to azithromycin was reported in 7.1% of NG isolates nationally, increasing from being proportionally stable (3.9% to 4.7%) since 2019. Of NG isolates tested, 0.20% (20/10,204) exhibited high-level resistance to azithromycin (MIC value ≥ 256 mg/L), with cases reported across Australia, predominantly in New South Wales, Victoria and non-remote Western Australia. There were ten isolates detected in 2025 that had an extensively drug-resistant (XDR) phenotype: i.e., displaying both high-level resistance to azithromycin and decreased susceptibility to ceftriaxone (MIC ≥ 0.125 mg/L). When added to the 14 XDR isolates reported during 2022-2024, this brings the total to 24 XDR NG isolates reported in Australia since 2022. Genomic analyses of the ten XDR isolates reported in 2025 indicated all harboured the mosaic penA 60.001 allele, with several differing sequence types (ST) identified. By contrast, during 2022 and 2024, XDR NG sequence types were limited to ST-16406, consistent with reports from Europe and England. Travel information, where available, indicates infections in 2025 were associated with travel to Southeast Asia but also arose where no travel was involved. In 2025, penicillin resistance was found in 23.4% of gonococcal isolates, and ciprofloxacin resistance in 59.3% of isolates where tested, although there was variation by jurisdiction particularly in remote settings, where acquisition of cultures for antimicrobial susceptibility testing is low. Tetracycline resistance has been included in surveillance in the AGSP in recent years, coincident with increasing use of doxycycline post-exposure prophylaxis for syphilis and chlamydia. Nationally 36.2% of NG isolates in 2025 were tetracycline resistant, with variation by jurisdiction. No isolates were resistant to spectinomycin; data for gentamicin, whilst no breakpoints are defined, are reported by the AGSP as these data are reportable to the WHO Global Antimicrobial Resistance and Use Surveillance System (GLASS). The emergence of antimicrobial resistant NG in Australia has largely occurred through importation, spread and local transmission. In 2025, in Australia and overseas, increased detection of drug-resistant NG isolates is of significant concern as the threat for the future of the current recommended therapeutic agents is increasingly evident, and no ideal alternate therapeutic agent has been identified. Disease prevention strategies under investigation for the future have included the MenB-4C vaccine, designed to protect against meningococcal disease. Despite early promise, recent results from a large Australian trial indicate the MenB-4C vaccine is not effective at preventing gonorrhoea in men who are at high risk of infection. The AGSP continues to monitor antimicrobial resistance and to identify emerging resistant clones by enhanced surveillance approaches, to inform strategies for disease management and treatment of gonorrhoea in Australia.

In the wake of the coronavirus disease 2019 (COVID-19) pandemic, there have been dramatic changes in the testing protocols for respiratory illness. Laboratory identification of respiratory pathogens causing clinical symptoms has become more important in the post-COVID-19 era, both for epidemiological and clinical reasons. This is particularly the case for respiratory syncytial virus (RSV) where a number of preventatives are at the point of clinical translation. The laboratory diagnosis is one of the critical elements in understanding the disease burden of respiratory pathogens and the effectiveness of preventatives. The aims of this study were to understand current laboratory testing and reporting practices across Australia.

Important uncertainties remain regarding the role of coinfection, asymptomatic carriage, and the contribution of toxigenic Corynebacterium diphtheriae to clinical disease. This Letter to the Editor highlights several key unanswered questions and emphasises the need for a better understanding of this re-emerging infection to inform diagnosis, microbiological testing, clinical management, and public health responses.

This report describes unusually persistent transmission of norovirus in a hospitality setting in Victoria, Australia. In September 2023, the Victorian State Government Department of Health was notified of six gastroenteritis outbreaks associated with events held at a single function venue. Genomically identical norovirus genogroup II (GII) was detected from cases in five of the outbreaks. No statistically significant association with illness was found for any food item. Information collected through staff interviews provided evidence of food handlers and wait staff continuing to work while infectious, likely resulting in sustained transmission through person-to-person routes as well as through potential contamination of the environment.

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.

This summary report on vaccine preventable diseases in Australia is the latest in a series of multi-year surveillance reports that bring together the three most important national sources of routinely-collected data on VPDs (notifications, hospitalisations and deaths) and serve as a resource to support surveillance and control of VPDs in Australia. This report focuses on the four-year period 1 January 2019 to 31 December 2022 with longer term trends also presented. Two VPDs are included for the first time: coronavirus disease 2019 (COVID-19) and Japanese encephalitis virus (JEV) infection.

This report describes influenza surveillance activities in Australia in 2022 to 2023. Data were extracted from several sources constituting the National Influenza Surveillance Scheme. Following the relaxation of public health and social measures which had been applied in Australia in response to the coronavirus disease 2019 (COVID-19) pandemic in 2020 and 2021, the influenza seasons in 2022 and 2023 were characterised by high activity overall, with 1.4 and 1.8 times the number of laboratory-confirmed influenza notifications than those of the 2015-2019 pre-pandemic five-year mean, respectively. There were differences in the timing of the 2022 and 2023 influenza seasons compared to most pre-pandemic years, with earlier season starts and earlier peaks (approximately six to eight weeks earlier than in pre-pandemic years). There was also considerable variation in the timing of peak influenza activity between the states and territories, particularly in 2023. Notification rates were highest in the 5-9 years age group, with rates in this age group about two and a half times as high in 2022 and three times as high in 2023 as the overall notification rate in the corresponding years. Influenza A(unsubtyped) comprised most notifications in 2022 and 2023. Of the remaining samples, influenza A(H3N2) was dominant in 2022; however, in 2023, there was substantial circulation of influenza B, which predominantly affected children and younger adults, and of A(H1N1). Sentinel surveillance supports the assessment that both the 2022 and 2023 influenza seasons were characterised by early, high activity. High notification rates were also reflected in increased sentinel hospital admissions with confirmed influenza in 2023, particularly among children. The burden placed on sentinel hospitals due to people admitted with influenza was moderate in 2022 but high in 2023. Severity, measured through the proportion of patients admitted to sentinel hospital intensive care units, was moderate in both years and consistent with historical estimates. Influenza was recorded as the underlying cause of death in 0.16% of all deaths that occurred in 2022, and 0.24% of all deaths in 2023. Overall, the 2022 influenza season had high activity with low-to-moderate severity, while 2023 had high activity with moderate severity.

Two incursions of high pathogenicity avian influenza (HPAI) A(H5N1) clade 2.3.4.4b in vagrant birds were identified in the Hunter New England region of New South Wales, Australia on 28 June 2026 and 10 July 2026. These were the first detections of the virus in New South Wales and occurred shortly after the first Australian detection in June 2026. The Hunter New England Population Health Unit managed human contacts of the infected birds using a contact management system designed and purpose-built by the Unit. We report on the public health response and opportunities for improvement.

Vaccination plays a pivotal role in protecting people who are immunocompromised, and who may therefore be at increased risk of infectious diseases, including vaccine preventable diseases (VPDs). However, there are special challenges in clinical practice and the development of immunisation policies to accurately address the vaccination needs of this heterogeneous population. This review aims to highlight the immunisation needs and challenges of immunocompromised populations, and to summarise the rationale behind the immunisation recommendations for these populations in Australia. The chapter Vaccination for people who are immunocompromised, in the Australian Immunisation Handbook, was recently updated by the Australian Technical Advisory Group on Immunisation (ATAGI). The updated chapter introduces new categorisation and risk classification for various types of immunocompromise, alongside the principles of immunisation. When planning immunisation for immunocompromised people, it is crucial to consider their underlying diagnoses, exposure to immunosuppressive therapies, susceptibility to VPDs, and their immune response to vaccination. Strategies to improve protection for immunocompromised persons include booster doses or altered schedules of routine vaccines; additional vaccines to prevent specific VPDs; and complete revaccination following immune reconstitution. Several national and jurisdictional vaccination programs have been implemented for immunocompromised populations (alongside other priority populations); however, monitoring vaccine coverage in these groups is challenging, and strategies to improve coverage are needed. There are significant evidence gaps in vaccine research for immunocompromised people, particularly regarding the optimal timing and scheduling of vaccinations to ensure maximum efficacy and safety. Future research should prioritise the inclusion of immunocompromised people in clinical trials and should integrate evidence from post-licensure use through data linkage. Emerging vaccine technologies may enable the development of more immunogenic vaccines or may offer more effective vaccination strategies for better protection against VPDs in immunocompromised people.

The reference laboratories of the Australian Meningococcal Surveillance Programme (AMSP) report data on the number of cases of invasive meningococcal disease (IMD) confirmed by laboratory testing using culture and molecular based techniques. Data contained in quarterly reports are restricted to a description of case numbers of IMD by jurisdiction and serogroup, where known and expanded in 2024 to include antimicrobial resistance data for ceftriaxone, penicillin, ciprofloxacin and rifampicin. A full analysis of laboratory confirmations of IMD in each calendar year are contained in the AMSP annual reports.