The effect of COVID-19 public health measures on nationally notifiable diseases in Australia during 2020 and 2021

The novel coronavirus disease 2019 (COVID-19) pandemic prompted Australia to implement large-scale domestic lockdowns and halted international travel. However, the impact of these measures on national notifiable diseases is yet to been fully examined. In this paper, we expand on a preliminary analysis conducted in 2020, and conducted a retrospective, observational study using nationally notifiable disease surveillance system (NNDSS) data to examine if the changes identified in the first half of 2020 continued in Australia through wide-scale public health measures. We found that there was an overall reduction in most of Australia's nationally notifiable diseases over the two pandemic years during which wide-scale public health measures remained in operation, particularly for 23 social and imported diseases. We observed an increase in notifications for psittacosis, leptospirosis and legionellosis during these years. The public health measures implemented in 2020 and 2021 (including lockdowns, mask mandates, and increased hand and respiratory hygiene) may have contributed to the observed notification reductions. The outcomes of these measures' implementation provide insights into broader communicable disease control for mass outbreaks and pandemic responses.