COVID‐19 outbreaks in aged‐care facilities in Australia

Abstract Background Aged‐care facilities (ACF’s) provide unique challenges when implementing infection control methods for respiratory outbreaks such as COVID‐19. Research on this highly vulnerable setting is lacking and there was no national reporting data of COVID‐19 cases in ACFs in Australia early in the pandemic. We aimed to estimate the burden of aged‐care worker (ACW) infections and outbreaks of COVID‐19 in Australian aged‐care. Methods A line list of publicly available aged‐care related COVID‐19 reported cases from January 25 to June 10, 2020 was created and was enhanced by matching data extracted from media reports of aged‐care related COVID‐19 relevant outbreaks and reports. Rate ratios (RR) were used to predict risk of infection in ACW and aged‐care residents, and were calculated independently, by comparing overall cases to ACW and aged‐care residents' cases. Results A total of 14 ACFs with COVID‐19 cases were recorded by June 2020 nationwide, with a high case fatality rate (CFR) of 50% (n = 34) and 100% (n = 3) seen in two ACFs. Analysis on the resident risk found that the COVID‐19 risk is 1.27 times higher (unadjusted RR 1.27 95% confidence interval [CI] 1.00 to1.61; P = 0.047) as compared with the risk of infection in the general population. In over 60% of cases identified in ACFs, the source of infection in the index case was unknown. A total of 28 deaths associated within ACFs were reported, accounting for 54.9% of total deaths in New South Wales and 26.9% of total deaths in Australia. Conclusions This high‐risk population requires additional prevention and control measures, such as routine testing of all staff and patients regardless of symptoms. Prompt isolation and quarantine as soon as a case is confirmed within a facility is essential.

social distancing is difficult due to shared communal areas and closecontact living, presents major barriers to infection control as well, contributing to the overall burden in these settings. 9 A wide variation in the proportion of residents and staff being infected and in the spread of the disease between different ACFs has been reported. 4,6,7 ACFs provide unique challenges when implementing infection control methods, especially considering respiratory outbreaks. The significant levels of close-contact physical care 5 combined with a less trained and prepared workforce 10 who often face more difficulty accessing personal protective equipment (PPE), create difficulties in infection control measures. Not all aged-care workers (ACWs) are required to be registered nurses with skilled health training and a very small percentage are qualified nurses. 11 Studies on this high-risk population is lacking, and there was previously no national reporting of data of ACF cases of COVID-19. Despite the reporting of multiple COVID-19 outbreaks in ACFs nationwide, the burden of COVID-19 on Australian aged-care has not been identified. 12 We aimed to estimate national COVID-19 outbreaks and cases in ACFs in Australia using open-source data during the first wave of COVID-19 in Australia.

| Data collection and data linkage
We collected publicly available data on Australian COVID-19 patients and outbreaks reported by National and state/territory Governments and the media between January 25, 2020 and June 10, 2020. Cases  ACF outbreaks were matched using date, location (state/territory and city), the name of the ACF, number of cases, patient age, number of deaths, and occupation as an ACW. This information was then matched between media reports found in the Google search and outbreak reports found on official government websites based on the matching criteria matrix in Table 1. A case is considered a high probability match if fulfilling at least one criterion from all Groups 1, 2, and 3; a medium probability match if fulfilling at least one criterion from Groups 2 and 3; and otherwise, a low probability match. Only cases with high probability matching were included for analysis. For the purposes of this study, ACFs were deidentified in reporting the results.

| Data analysis
Cumulative incidence rates of infections for ACWs were calculated using reported cases and the remaining total cases as the numerator and denominator data from the Australian Government, Institute of Health and Welfare Aged-Care Data Services (AIHW GEN) (39). This was then repeated separately for aged-care residents. The general population rates were calculated using notified national cases as the numerator and the Australian population as the denominator. Rate ratios (RRs) were calculated by comparing overall rates with those in ACW and aged-care residents. Due to the absence of a complete data set where the age for each patient could be conclusively determined, the data were not age stratified. An epidemic curve was plotted to describe the distribution of aged-care cases for both isolated cases and outbreaks, against Australia's nationwide epidemic curve.
T A B L E 1 High, medium, and low probability matching criteria for matching aged-care related COVID-19 cases   A total of 55 ACW cases were reported from these facilities Descriptive information for ACFs outbreaks is summarized in   A potential limitation of the risk analyses conducted for this study

| Sources of infection among ACWs
were based on open-sourced data for ACF cases, which may vary depending on each state's individual data publishing policies. This is likely to lead to underestimation of cases in ACF. We also used media reports, which have not been verified. In most cases, however, there were multiple media reports about each outbreak, often with a quote from health officials. However due to the absence of a complete data set where the age for each patient could be conclusively determined, the data were not age stratified. There is also a potential effect of testing rates on the identification of COVID-19 cases. We accounted for this by representing the daily testing rates in conjunction with the daily ACF and ACW infections reported. A large proportion of ACW and ACF infections had an unknown source, and we were unable to obtain data on source of infection, nor verify reported sources. This highlights the need for proper and detailed outbreak investigation and contact tracing during aged-care outbreaks. This study did not investigate the second wave in Melbourne. This study may not be generalizable to other countries or settings, with different COVID-19 epidemiology, PPE policies, and health systems.

| CONCLUSION
ACFs are a high-risk setting for COVID-19 outbreaks. Fourteen outbreaks of COVID-19 occurred in Australia by June 2020, with a high CFR. Commonly, the source of initial infection was unknown.
Interventions for preventing COVID-19 transmission needs to consider the high possibility of asymptomatic transmission, testing of all residents and staff during an outbreak, and prompt isolation and quarantine as soon as a case is confirmed within a facility. This high-risk population requires additional prevention measures, which may be tailored to the level of community transmission. We also recommend registration or enumeration of the aged-care workforce for each state or territory.