A brief thread about what might be coming up in Australia to control #COVID19. I'll emphasise that what interventions are likely to work depend very much on the situation at the time, and not all are being considered in the near future, or even at all.
Some principles are that interventions should be proportionate to the risk, reasonable and the least restrictive option, considers equity and burden, and evidence based. This obviously is difficult with uncertain parameters and imperfect surveillance.
Most of these have been considered in the context of influenza, but there are some key differences with COVID. The incubation period is much longer (6-7 days vs 1-2 days). Probably less pre-symptomatic transmission than flu. Kids don't seem to get severe disease.
Border measures are likely to become less useful once transmission is widespread (as AHPPC noted last week), and particularly if transmission has been established in Australia.
health.gov.au/news/australia…
health.gov.au/news/australia…
Case finding and isolation. Trying to test widely (esp along transmission chains) to find cases and stop onward spread. This includes isolation in hospital, or at home, or in other settings. Capacity to test quickly an obvious constraint.
Contact tracing and quarantine (note isolation is for sick cases, quarantine for potentially incubating contacts). Studies suggest this would be sufficient alone if >80% contacts traced and quarantined before getting sick (5-7 days). A big ask - average number of contacts is ~20
Personal hygiene. We've all seen the messages about hand hygiene, cough etiquette and not touching your face. Everything helps, and large scale behaviour change, although difficult, can be effective on a population level and potentially sustainable.
Social distancing includes a variety of broad measures to slow spread, including school or workplace closure, cancelling large gatherings, reducing public transport, getting people to work from home where possible. They don't require finding cases and contacts.
School closure. May be proactive (before cases occur) or reactive (after cases identified). Very disruptive and many flow on effects (eg kids looked after by grandparents, impact on healthcare workers). Also hard to know when to open again.
For #COVID19, kids do appear to get infected but don't get very sick, making this decision difficult. Several countries have closed schools, including Japan. medrxiv.org/content/10.110…
Other school interventions. Many possible, as I mentioned yesterday.
Workplace closure. Again, difficult prospectively, but may be required in response to cases. The value of this obviously depends on many factors - size of workplace, crowding, vulnerable populations.
Cordon sanitaire. Lockdown of a region - used in Hubei, and now northern Italy. The nuclear option of public health interventions with a long history. bbc.com/news/uk-englan…
Cancelling mass gatherings. A difficult one to get right, as you don't want to cancel everything before anything happens, but on the other hand, you don't want to be Philadelphia
Different countries have taken different approaches. China has pretty much used all of these turned up to 11. Singapore and Hong Kong SAR have done quite well using case finding/isolation and contact tracing mostly, but that is clearly more feasible in small city-states/regions
The aim is to flatten the curve, but paradoxically, the more successful this is, the longer this goes on for. None of these are perfect and can be partial (eg chasing household but not other contacts) but even if control isn't possible it can buy time.
In addition to previous empiric research, mathematical modelling, such as that done in Australia by @PRISM_CRE led by Jodie McVernon, @j_mccaw and @rob_mathbio help us understand how and when to deploy these interventions and their likely effectiveness.
Nice article with @j_mccaw explaining modelling: mobile.abc.net.au/news/health/20…
Wow, glad everyone's found this useful. I should point out that this is the Twitter summary of the interventions in the AHMPPI (pandemic influenza plan) adapted to COVID
www1.health.gov.au/internet/main/…
www1.health.gov.au/internet/main/…
And a few other local threads that might be useful - @drsarahmac on a few common questions:
And a previous thread on advice for non-ID specialists:
