Doherty Modelling–Final report to National Cabinet 5th November 2021


The modelling process was led by the Doherty Institute’s Director of Epidemiology, University of Melbourne Professor Jodie McVernon, and University of Melbourne Professor James McCaw and involves collaborative work conducted by multiple teams with specific expertise in infectious diseases modelling across six institutes and universities from around Australia.

Link to the modelling hub for a full list of collaborators

Doherty Modelling–Final report to National Cabinet 5th November 2021. Access here

Key messages

Work Package 1 – Modelling to inform review and refinement of public health response measures

  • Streamlined and focussed test-trace-isolate-quarantine (TTIQ) processes (supported by PHSMs) will be required for future public health responses to be effective and sustainable
  • We have previously shown that case-initiated contact tracing can support timely quarantine in times of system stress
  • Reduced contact tracing intensity and differential management of vaccinated individuals will help to ensure sustainable responses as caseloads increase
  • Focussed TTIQ with wrap around support will be needed in communities that remain at risk of higher transmission and/or clinical impacts
  • Ongoing data

Work Package 2 – Optimise vaccination at sub-jurisdictional level

1. First Nations Australians

  • High vaccine coverage can reduce transmission and health impacts in urban and remote communities
  • Reactive vaccination is a useful adjunct to community engaged and led outbreak response
  • Providing access to effective treatments will further promote health outcomes

2. Local Government and small area effects

  • Baseline transmission potential (TP) differs by small area, as do vaccine and PHSM impacts (ability to work from home)
  • Focussed TTIQ and wrap around supports will be needed to constrain TP in high-risk areas and. may include additional measures in schools and workplaces

3. Schools

  • Early infection detection and high vaccine coverage markedly reduce outbreak risk
  • Allowing ongoing school attendance for class contacts of a case through a ‘test to stay’ strategy achieves equivalent outbreak containment to home quarantine and enables face to face learning
  • School based measures will have maximum utility in areas with higher than average transmission
  • Regular screening of students in areas at risk of outbreaks can result in even fewer infections and in-person teaching days lost

Work Package 3 – Review border measures and arrivals pathways

  • Vaccination reduces the risk of infected people being released from quarantine into the community, mitigating against shorter duration
  • These importations do not materially impact on established epidemics or lead to large outbreaks at the defined Phase C coverage threshold of 80%, when combined with ‘low’ PHSMs
  • These findings assume consistent vaccine protection and virus characteristics identical to those assumed for the Delta variant (ie no more transmissible, and equally preventable by vaccines)

Revisions to parameter assumptions

  • Mixing, vaccine effectiveness and clinical severity parameters have been updated for this phase of work, based on latest available evidence
  • Previous recommendations of 70 and 80% vaccine coverage thresholds for National Plan transition phases remain robust