A GIS-Based Spatiotemporal Analysis of the Relationship between the Outbreak of COVID-19, Delta Variant and Construction in Sydney and Melbourne

The outbreak of the Delta Variant of COVID-19 presents a natural experiment without modern precedent. As authorities scrambled to control the spread of the disease in Australia's largest cities, construction workers were allowed to keep working on site without the benefit of mandatory vaccination, unlike their peers in healthcare, defense, education or aviation. Using publicly available COVID-19 surveillance data, we analyzed the geographic spread of the Delta Variant and its relationship with construction in both cities. The period of this study covers the identification of the first case of community transmission to the achievement of 90% full vaccination in the eligible population. We show how the risk profile of construction workers varies according to socio-economic status such that Machinery Operators and Drivers were most at risk, followed by Laborers, owing to where they tend to live in each city. Moreover, these highly mobile workers may unknowingly serve as vectors for the spread of infectious disease to the most vulnerable communities in an urban setting. Remarkably, we also found that the risk profile of construction businesses can also be described similarly in terms of annual income. Sole traders and small businesses were mostly located in vulnerable areas, which presents threats to business continuity that public policy must address. We observed that the first eight weeks of an outbreak are critical; after this time, vulnerable workers and most construction businesses will see steep rises in their exposure to the risk of infection until the disease is brought under control. Accordingly, we recommend short, sharp pauses of all construction works on site to control the spread of future pandemic outbreaks once cases of community transmission are detected. Fiscal policy must support workers and small business owners, so they are not forced to choose between their health and earning a living during these periods. The government and trade unions must commit to mandatory vaccination for construction workers to safeguard their communities. Health authorities must continuously engage with particularly vulnerable workers as immunity wanes and vaccine boosters become necessary. Digital disinformation must be tirelessly countered by consistent expert medical advice at all levels of the industry.