The epidemiology of notifiable diseases in Australia and the impact of the COVID-19 pandemic, 2012–2022

Background Infectious disease surveillance tracks disease epidemiology and informs prevention and control. Public health measures implemented in Australia during the COVID-19 pandemic (2020 to 2022) affected infectious disease epidemiology. We examined notifiable disease epidemiology in Australia from 2012 to 2022, evaluating disease trends and pandemic impacts. Methods We analysed case notifications supplied to the Australian National Notifiable Disease Surveillance System (NNDSS) from 1 January 2012 to 31 December 2022. The annual incidence and notification incidence trends were calculated and the average changes in annual incidence were investigated by Poisson regression. Results Over the study period, there were 14,087,045 notifications of 68 diseases. Respiratory diseases were the most commonly notified disease group (83% of all notifications) and vector-borne diseases the least (< 1%). The ten highest-incidence diseases comprised 97% of all notifications over the study period, with COVID-19 alone accounting for 72%. Notifications were most common among the 20–39-year age group (37%). From 2012–2019, notification incidence of gastrointestinal, respiratory and sexually transmissible infections increased, whereas for bloodborne viral hepatitis, vector-borne diseases and imported diseases it decreased. From 2020–2021, average notification incidence of most non-COVID-19 respiratory diseases decreased compared to the 2012–2019 period; sexually transmissible infections notification incidence remained fairly stable; notification incidence of some gastrointestinal diseases increased while others decreased; and notification of imported diseases markedly decreased. A rebound in notification incidence was seen for most diseases in 2022. Conclusions Prior to the COVID-19 pandemic, most notifiable diseases had increasing notification incidence, except for bloodborne viral hepatitis, vector-borne diseases and imported diseases. COVID-19-related public health measures had variable impacts on notifiable diseases.