September 23, 2020
Professor Lewin is also the Chief Investigator of the Australian Partnership for Preparedness Research in Infectious Disease Emergencies (APPRISE), and Professor Kaldor is an APPRISE investigator.
This was first published in the Australian Financial Review.
With few or no cases of community transmission in seven of Australia’s eight jurisdictions, and the strong control measures in Victoria showing clear signs of success, we will soon be in a position to again look at Australia as one country. Introducing a hot spot approach is getting increasing attention as a way to return us to the new normal.
A hotspot, also known as a “spatial case cluster”, can play an important role in controlling infectious disease outbreaks. It attracted lots of attention early in the COVID-19 pandemic, when state borders began to close in March. It was again in the headlines recently when national cabinet discussed a plan to move towards reopening borders between states and territories through an agreed definition of a local outbreak of COVID-19.
Big or small, all outbreaks of COVID-19 have distinct features and require responses that are not only evidence-driven and co-ordinated, but also locally nuanced. The idea behind a hotspot approach is that if we know with local precision where COVID-19 cases are occurring, they can be managed locally and there should be no need to label whole states or territories as affected, and we can negotiate cross-border travel arrangements accordingly.
As with many appealingly simple solutions, the devil is often in the detail: for instance, how to define “hotspot”? Harvard University produces a colour-coded risk-assessment map for domestic travellers, giving daily case counts of COVID-19 down to the level of counties (analogous to our local government areas): red for no-go zones/hotspots, progressing to “good to go”/green – which represents one case per 100,000 population. To put this in perspective, that “safe’’ green figure is double the rate of infection in Melbourne.
Hong Kong and Singapore use a much more fine-grained approach that goes down to the level of a residential building as a hotspot. In Australia, this approach may well have privacy concerns.
We need something in between.
Second, how can we be sure the testing is effectively covering the population, so that we can have confidence that hotspots will actually show up on the maps? Public health guidance encourages all people with new respiratory symptoms to get tested and self-isolate until they know their results, but it appears only a minority are getting tested. NSW has reported that the coverage of testing has varied considerably across local government areas. An area with cases may fail to register as a hotspot if the testing coverage is low.
And even where we do have good testing coverage, not all cases should be counted equally. A local area with five new cases may at first seem to be a clear cause for concern, but much less so if they were all in quarantine as known contacts when they were diagnosed.
Jurisdictions must be able to trust one another’s mechanisms that detect and manage hotspots.
Outside lockdown situations, defining hotspots based on where infected people live may overlook the equally important issue of where they acquired the infection. Workplaces, social venues or gyms may have far greater public health significance. Tracking spread from such venues becomes increasingly difficult if people can move freely across borders.
What would a hotspot approach look like in Australia? To reach agreement, it is likely the states and territories would want a definition that classified an area as a hotspot if there was any level of community transmission of infection.
Whatever the definition, it is clear any national system based on hotspots will require all jurisdictions to have mechanisms that deliver high levels of testing, rapid and comprehensive contact tracing and well-enforced quarantine of contacts. Furthermore, jurisdictions must be able to trust one another’s mechanisms that detect and manage hotspots. And the best way to achieve that is through regularly measuring and reporting of performance in as close to real-time as possible.
We are all on a potentially long road of COVID-19 outbreaks, with no certainty about when a vaccine will arrive. We need to put all options on the table to manage the ongoing emergency.
Everyone recognises that opening domestic borders will have substantial social and economic benefits, provided case numbers can be kept low. Opening borders will also free up border-control resources that can be used to enhance localised public health responses, including contact tracing that will need to operate effectively across borders.
A nationally agreed and transparently monitored approach to defining local hotspots, and how they are used in controlling movement of people, will help us all to achieve our goals of reconnecting as a country.