Influenza Surveillance and Vaccination Trends in Australia (2020–2025)

Introduction

Influenza is an acute respiratory infection caused by influenza viruses and is widespread across the globe. It is highly contagious and spreads easily from person to person, through droplets released when an infected individual coughs or sneezes. Each year, seasonal influenza affects approximately one billion people worldwide, with 3 to 5 million cases classified as severe. The virus is also responsible for an estimated 290,000 to 650,000 deaths from respiratory complications annually (World Health Organization, 2025). In Australia, Influenza is the leading vaccine-preventable disease. While it is often mild, it can also lead to severe complications, even in healthy individuals (Australian Government Department of Health and Aged Care, 2025). Influenza can affect anyone, but certain groups, like adults over 65, pregnant women, and Aboriginal and Torres Strait Islander (First Nations) peoples, are at greater risk of developing serious complications, including pneumonia. In some cases, influenza infection can be fatal (Australian Institute of Health and Welfare, 2025).

The monitoring of influenza trends is a cornerstone of Australia’s communicable disease control framework. Surveillance systems are vital for understanding the epidemiology and burden of seasonal influenza epidemics, supporting vaccine strain selection by providing virus isolates, and detecting emerging pathogens with the potential to cause pandemics (El Guerche-Seblain et al., 2021). The National Notifiable Diseases Surveillance System (NNDSS) is a nationwide program that supports all levels of public health by collecting, analyzing, and sharing data on infectious and certain noninfectious diseases. It enables coordinated monitoring and response efforts across local, state, national, and international levels. The NNDSS produces weekly and yearly reports on diseases classified as nationally notifiable by the Council of State and Territorial Epidemiologists (CSTE), with standardized case definitions (National Center for Health Statistics, 2023). During the COVID-19 pandemic, influenza circulation in Australia significantly decreased due to public health measures. In 2020 and 2021, flu cases were extremely low. Since 2022, influenza has returned strongly, with earlier and significant seasons. The 2024 season had a record number of confirmed cases but fewer deaths than in some past severe seasons. Flu season lengths have varied post-pandemic, with 2022 being short and 2023–2024 more typical (Barr, 2024).

Vaccination is the most effective preventive strategy against influenza. Australia’s national immunisation program provides free influenza vaccination for at-risk groups, including children aged six months to under five years, adults aged 65 years or over, Aboriginal and Torres Strait Islander people aged 6 months and over, pregnant women, and individuals with chronic medical conditions (Australian Government Department of Health, Disability and Aged Care, 2025).

The implementation of vaccination programs is strongly influenced by public perception of disease severity. Since the COVID-19 pandemic, influenza vaccination efforts in Australia have faced challenges despite the availability of free vaccines for high-risk groups. Although vaccination rates reached a peak in 2020, due to increased public health awareness, the vaccination rates have since decreased or leveled off, with only 26% of young children and 60.5% of older people vaccinated in 2024. This decrease in coverage continues regardless of the evidence of moderate vaccine efficacy and the subsequent number of cases and hospitalisations of influenza, which rise after the pandemic, highlighting the need to maintain robust immunisation coverage  (Barr, 2024).

The objective of this report is to analyse trends in influenza notifications, vaccination coverage, and hospitalisations in Australia between 2020 and 2025. The report also aims to identify gaps in vaccination uptake and surveillance limitations, and to provide evidence-based recommendations for strengthening public health responses to influenza in Australia.

Methods

This report draws on two key data sources. The primary source is the National Notifiable Diseases Surveillance System (NNDSS), which provides a dataset of  lab-confirmed influenza cases from 2008, broken down by month and patient variables. While it supports outbreak the response and public health policy, data quality varies because of inconsistent reporting systems. Annual reports are peer-reviewed and aimed at public health professionals, making them suitable for expert audiences but less accessible for general public. Visualisation tools improve usability, but understanding raw datasets may require technical knowledge. However, data consistency efforts are ongoing. Compared to other sources, NNDSS provides timely, structured, but sometimes incomplete data (Australian Government Department of Health, Disability and Aged Care, 2025).

The secondary source is the Immunisation Coalition, a non-profit organisation which provides accessible, evidence-based educational resources on vaccines, targeting both healthcare professionals and the public. While its content is guided by experts, it is not peer-reviewed or a primary data source. Unlike NNDSS, it offers limited original data but excels in communication, awareness, and advocacy. Its information is easy to understand and well-suited for its target audience (Immunisation Coalition, n.d.).

The diagrams in this report were produced to summarise influenza notifications, hospitalisations, and influenza vaccination coverage between 2020 and 2025. The graph illustrating influenza notifications was created in Microsoft Excel, which allowed for the clear visualisation of trends over time. The tables were created in Microsoft Word to present influenza-associated hospitalisations and vaccination coverage in Australia in a concise format

Results and Discussion

Influenza Notifications

Data from the NNDSS show 313,452 laboratory-confirmed influenza cases in 2019, before a sharp decline in 2020 when 21,343 cases were reported, and in 2021 when only 749 cases were recorded. Notifications rebounded in 2022 with 233,446 cases and rose further to 289,129 in 2023. In 2024, influenza activity remained high with 343,501 cases. By 8 September 2025, 344,325 cases had already been reported, exceeding the total for the entire previous year (Barr, 2024; Immunisation Coalition, 2025).

Figure 1. Influenza Notifications in Australia, 2020–2025
Adapted from Barr (2024) and Immunisation Coalition (2025).

Hospitalisations of influenza patients

The data indicate a significant fluctuation in 2019 and 2025 influenza-associated hospitalisations. Hospitalisations were up in 2019, with 3,915 admissions. When the COVID-19 pandemic occurred, hospitalisations dropped significantly in 2020, with 15, and in 2021, with no hospitalisations, as a response to border closures, mask-wearing, and restrictions on movement. When restrictions during 2022 were removed, there was a resurgence in 2022 in influenza activity, resulting in 1,832 hospitalisations. This trend kept on increasing, with 3,480 in 2023 and 3,709 in 2024, reaching close to levels seen before the pandemic (Barr, 2024).

By 2025 (to mid-year), the situation escalated, with 5,558 hospitalisations reported, already exceeding earlier years. Alarmingly, the majority of these patients were unvaccinated,  highlighting a close association between low vaccine coverage and greater severity of seasons of influenza (Queensland Government, 2025).

Table 1. Influenza-Associated Hospitalisations in Australia, 2020–2025

Adapted from Barr (2024) and Queensland Government (2025).

Influenza Vaccination Coverage in Australia (2020–2025)

Influenza vaccination coverage has fluctuated since 2020, with an unusually high uptake early in the pandemic, peaking in 2022 among older adults. However, the coverage declined from 2023 onward, reaching just 32% overall in 2024, with children and young adults showing particularly low rates by mid-2025.

Table 2. Influenza Vaccination Coverage in Australia, 2020–2025

Adapted from Barr (2024)

Recommendations

Strengthen Vaccination Campaigns

Public messaging should emphasize that influenza remains a serious illness, distinct from COVID-19, and that vaccination is important every year. Tailored communication campaigns that target younger adults and culturally diverse communities could help in addressing complacency and vaccine hesitancy. For example, peer-to-peer and service-provider engagement has been demonstrated to be a localized and trust-based approach that can be used to re-establish trust and vaccine confidence in vulnerable populations (Shah & Nguyen, 2025).

Expand Access and Incentives

Free vaccination could be extended to all the age groups, not only those at high risk. Workplaces, pharmacies, and schools should be used as convenient vaccination sites. Uptake may be further boosted by incentive schemes, like a Medicare rebate or employer-led campaign. Gualano et al. (2022) emphasized that free on-site vaccination can be an effective instrument in ensuring that people adhere to the vaccination campaigns and administration of all necessary doses according to vaccine administration plan.