The effect of public health interventions on COVID-19 incidence in Queensland, Australia: a spatial cluster analysis

Abstract

Background

Using SaTScan™ Geographical Information Systems (GIS), spatial cluster analysis was used to examine spatial trends and identify high-risk clusters of Coronavirus 2019 (COVID-19) incidence in response to changing levels of public health intervention phases including international and state border closures, statewide vaccination coverage, and masking requirements.

Methods

Changes in COVID-19 incidence were mapped at the statistical area 2 (SA2) level using a GIS and spatial cluster analysis was performed using SaTScan™ to identify most-likely clusters (MLCs) during intervention phases.

Results

Over the study period, significant high-risk clusters were identified in Brisbane city (relative risk = 30.83), the southeast region (RR = 1.71) and moving to Far North Queensland (FNQ) (RR = 2.64). For masking levels, cluster locations were similar, with MLC in phase 1 in the southeast region (RR = 2.56) spreading to FNQ in phase 2 (RR = 2.22) and phase 3 (RR = 2.64). All p values <.0001.

Conclusions

Movement restrictions in the form of state and international border closures were highly effective in delaying the introduction of COVID-19 into Queensland, with very low levels of transmission prior to border reopening while mandatory masking may have played a role in decreasing transmission through behavioural changes. Early clusters were in highly populated regions, as restrictions eased clusters were identified in regions more likely to be rural or remote, with higher numbers of Indigenous people, lower vaccination coverage or lower socioeconomic status.

Keywords:

• COVID-19
• Geographical Information System (GIS)
• spatial cluster analysis
• non-pharmaceutical interventions
• high-risk clusters

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are from publicly available sources. COVID-19 incidence data for Queensland, Australia are available from the COVID-19 Resources Open Data Portal from the Queensland Government repository (CC BY 4.0) (https://www.data.qld.gov.au/dataset/queensland-covid-19-case-line-list-location-source-of-infection/resource/1dbae506-d73c-4c19-b727-e8654b8be95a) [54]. All Australian SA2 population estimates data for 2021–2022 are available for download from the Australian Bureau of Statistics (ABS) data repository (CC BY 4.0) (https://www.abs.gov.au/statistics/people/population/regional-population/2021-22/32180DS0001_2021-22r.xlsx) [55].

Additional information

Funding

This research did not receive any specific funding or grants. HM was supported by the Australian Government Research Training Program (RTP) Stipend Scholarship.