As of July 2021, there is a continuing outbreak of the B.1.617.2 (Delta) variant of SARS-CoV-2 in Sydney, Australia. The outbreak is of major concern as the Delta variant is estimated to have twice the reproductive number to previous variants that circulated in Australia in 2020, which is worsened by low levels of acquired immunity in the population. Using a re-calibrated agent-based model, we explored a feasible range of non-pharmaceutical interventions, in terms of both mitigation (case isolation, home quarantine) and suppression (school closures, social distancing). Our nowcasting modelling indicated that the level of social distancing currently attained in Sydney is inadequate for the outbreak control. A counter-factual analysis suggested that if 80% of agents comply with social distancing, then at least a month is needed for the new daily cases to reduce from their peak to below ten. A small reduction in social distancing compliance to 70% lengthens this period to 45 days.

翻译：截至2021年7月,澳大利亚悉尼继续爆发SARS-CoV-2的B.1.617.2(Delta)变体,引起重大关切,因为三角洲变体估计是2020年在澳大利亚传播的先前变体的生殖数的两倍,而2020年澳大利亚传播的变异体的生殖数因人口获得的免疫率低而恶化。我们采用重新校正的代理模式,探索了可行的非药物干预范围,包括缓解(隔离病例、家庭检疫)和抑制(学校关闭、社会动荡)等。我们现在的预测模型显示,悉尼目前取得的社会动荡程度不足以控制爆发。一个反事实分析表明,如果80%的代理人遵守社会动荡,那么新的日常案例至少需要一个月的时间才能从高峰减少到不足十天。在此期间,将社会动荡的遵守率小幅降低到70%到45天。