Summary
The COVID-19 pandemic was a global emergency impacting individuals and placing significant strains on our health and support systems. Large databases that link COVID‑19 case information with data on health and support services and mortality have been used internationally to assess the impacts of COVID-19. In Australia, the COVID-19 Register was established to offer researchers this opportunity.
This report examines hospitalisations and deaths for people with COVID-19 (excluding Western Australia) during the first 3 years of the pandemic in Australia, with a focus on the height of the pandemic when the Omicron subvariant of the virus emerged and dominated. The role of COVID-19 vaccination and antiviral use was also examined.
There are several important considerations to note when interpreting information presented in this report. For example, some COVID-19 cases may not have been identified (not tested) or reported to the notifiable diseases’ register, see Technical notes for details.
Key findings
More than 1 in 3 Australians (8.5 million) (excluding Western Australia) had COVID-19 that was notified to health officials between 2020 and 2022 (see Technical notes for more details on data source and coverage). Of these, 97% experienced COVID-19 during the Omicron period (from mid-December 2021 onwards).
An estimated 4.8% had reported re-infection by the end of 2022, and were highest among females (5.4%) and young adults aged 20–29 (7.4%). Reinfection declined with increasing geographical remoteness (from 4.9% of people in Major cities to 3.3% in Remote and very remote areas) and increasing socioeconomic group (from 5.3% for the lowest group to 4.5% for the highest group).
Among people with COVID-19, hospitalisations related to COVID-19 and COVID-19 case fatality rates increased with age
Among people who had at least one COVID-19 notification during the Omicron period, 1.9% were admitted to hospital with a COVID-19 related illness (excluding same day hospitalisations), with a median stay of 5 days. The rate of hospitalisation increased with age – from 1.5% of people (or 1 in 69 people) aged under 20 to 12% of people (or 1 in 8 people) aged 80 or over.
Among those admitted to hospital during the Omicron period, 2.4% involved an intensive care unit (ICU) stay, 0.8% required ventilation and 2.2% died in hospital. Males were twice as likely to experience a severe hospital outcome (ICU stay and/or require ventilation) and/or a fatal outcome compared to females.
Over the first 3 years of the pandemic, the case fatality rate (the percentage of COVID-19 cases resulting in death due to COVID-19) was 0.13% (see Table 1). Although most deaths occurred during the Omicron period, the case fatality rate was 10 times lower in this period (0.11%) compared with the pre-Omicron period (1.1%). That is, although there were many more cases of COVID-19, people were less likely to die from COVID-19 during the Omicron period.
The case fatality rate during the Omicron period increased with age and overall was 1.4 times as high in males than females.
Among people with COVID-19, hospitalisations related to COVID-19 and COVID-19 case fatality rates were lower for those who were vaccinated
Among people with COVID-19, the rate of COVID-19-related hospitalisation was twice as high among people who were unvaccinated against COVID-19 (3.2%) compared to people who received one or more vaccine doses against COVID-19 (1.6%). Focusing on those aged 60 and over, the rate of COVID-19-related hospitalisations was 4 times as high among people who were unvaccinated against COVID-19 (14.8%) compared to people who received 3 or more doses (3.6%).
Across all age groups, case fatality rates were lowest in people who had received booster doses. For example, for people aged 60 and over who were vaccinated with 2 doses, the case fatality rate decreased by 73% compared to those who were unvaccinated (from 3.1% to 0.8%). This increased to an 87% reduction among people who were vaccinated with 3 doses (0.4%). For people aged 70 and over, death rates were lower for those who had their COVID-19 vaccination up to 3 months prior, compared to those where their last COVID-19 vaccination was 6 or more months prior.
COVID-19 related hospitalisation and case fatality rates were lower for those who were prescribed antivirals
COVID-19 antiviral treatments were made available through the Pharmaceutical Benefits Scheme (PBS) from March 2022 for people aged 70 or over, as well as other groups at higher risk of severe illness.
Among people with COVID-19 aged 70 or over, those who were prescribed antivirals were almost half as likely to be hospitalised for a COVID-19 related illness (43% reduction) compared with those who were not prescribed antivirals (3.8% and 6.6%, respectively).
Similarly among people with COVID-19 aged 70 or over, COVID-19 related deaths were 36% lower among people who were prescribed antivirals compared to those who were not (0.7% and 1.1%, respectively).
Among people with COVID-19, rates of COVID-19 related hospitalisations as well as overall case fatality rates varied by remoteness area and socioeconomic group
During the Omicron period, the COVID-19 case fatality rate was similar across Major cities and regional areas (0.11%) and slightly lower in Remote and very remote areas (0.08%). Case fatality rates decreased for people in the higher socioeconomic group – from 0.15% in the lowest group to 0.08% in the highest group.
During the Omicron period:
- People living in Remote and very remote areas were more likely to be hospitalised for a COVID-19 related illness, compared with people living in Major cities and regional areas. However, these hospitalisations had lower rates of severe and/or fatal outcomes (that is, intensive care stays, use of continuous ventilatory support and deaths in hospital).
- COVID-19-related hospitalisations decreased as socioeconomic group increased – from 2.7% of people with COVID-19 in the lowest group to 1.2% in the highest group. However, of those hospitalised, there was no difference in rates who experienced severe and/or fatal outcomes in hospital.
For people aged 70 and over, the use of COVID-19 antivirals reduced COVID-19 case fatality rates by 27% to 42% and COVID-19 related hospitalisation by 29% to 50% across all remoteness areas and socioeconomic groups.
Future opportunities for research
This report showcases the importance of linking data on notifiable infectious diseases with health system and mortality data to understand the impacts of infectious disease outbreaks.
At the time of writing, the COVID-19 Register is in the process of being integrated with AIHW’s National Health Data Hub to allow ongoing capacity for the data to be used to inform future public health investigation of pandemic responses and health system planning, and to assess the long-term impacts of COVID-19 on the population.