The ongoing COVID-19 Delta variant outbreak in Sydney has resulted in over 916 locally acquired active cases, with 75 individuals in hospital and 18 individuals in ICU, as of 16 July 2021.

Current restrictions, including mandatory face coverings and restrictions on indoor and outdoor gatherings, are in place until Friday 30 July, pending further advice from NSW Health.

In this analysis, data scientists from the Centre for Big Data Research in Health at UNSW have modelled the current outbreak and projected future cases based on five potential restrictions settings throughout August and September.

The five scenarios ranged in intensity from relaxed restrictions, similar to levels observed in early June, to a tighter lockdown, limiting social contacts even beyond current levels.

Observed and projected COVID-19 incidence in NSW (1 June - 1 October 2021)
xObserved and projected COVID-19 incidence in NSW (1 June - 1 October 2021)

The results indicate that continuing with restrictions at the level observed in the first half of July will not be enough to get the current outbreak under control. Getting the daily number of cases to a manageable level will require tighter restrictions and they will have to remain in place throughout August. 

Relaxing restrictions prematurely would result in an exponential rise in cases and ultimately prolong the duration of the outbreak.

The findings have not yet undergone peer review but have been made available online as a pre-publication analysis.

Lockdown restrictions updated on Saturday 17 July 2021: On 17 July, the NSW Government tightened the Greater Sydney lockdown restrictions which included the closure of non-essential retail businesses, a pause on construction activity, as well as restrictions on the movement of people who live in the local government areas (LGAs) of Fairfield, Canterbury-Bankstown and Liverpool. 

In response to the updated restrictions implemented on 17 July 2021, the researchers said, “Our study supports the recent tightening of restrictions in the Greater Sydney area and suggests these measures may have to stay in place for several weeks”