Changes in the Epidemiology and Outcomes of Emergency Department Presentations for COVID‐19 Infection, 2020 Through 2022, New South Wales, Australia: A Population‐Based Record Linkage Study

ABSTRACT Introduction Despite substantial human and financial resources invested in managing the pandemic, Australia lacks information on COVID‐19 epidemiology and health service use. This study aimed to describe the epidemiology of emergency department (ED) patients during the first 2 years of the pandemic in New South Wales (NSW), Australia (population ~8.2 million). Methods NSW respiratory infection‐related ED presentations were probabilistically linked with ambulance, admitted patient, notifiable condition, and death databases. ED patients with a linked COVID‐19 infection notification were included. The study spanned 2020 through 2022 and was divided into three phases according to the dominant virus variant: pre‐Delta, Delta, and Omicron. Results Of the 92,331 ED presentations with a linked COVID‐19 infection during the study period, most occurred during the Omicron phase (81%, 782%, 89%), followed by 9514 (10%) in the Delta and 1035 (1%) in the pre‐Delta phase. From the Delta to the Omicron phase, there was a substantial increase in the incidence of ED presentations among < 10 and ≥ 80‐year‐olds, with a 28‐fold and 20‐fold increase, respectively. Similarly, inpatient admissions increased 8‐fold and 17‐fold in these two age groups between the two phases. Over the same period, regional NSW residents experienced a 31‐fold and 15‐fold increase in ED presentations and inpatient admissions, while Greater Sydney residents experienced a 6‐fold and 3‐fold increase, respectively. Conclusions The study highlights the epidemiological shifts during the pandemic in NSW, especially the Omicron phase with marked increases in presentations and admissions, especially in the oldest adults and in children, and spread to regional areas.