"What's you exit strategy?" ... chatter about the MSMs overnight.

If you're Italy or the US, bumping along the top, you do not have one. If you do any less intervention than what you're currently doing, the thing will explode again, and off a much bigger base.

But in Australia our intervention has fully kludged the thing, so there is an exit. The professor has it; ease up but keep Rₜ safely below 1.0: https://twitter.com/cosmicpinot/status/1248556423279022080?s=20

(But note it's Rₜ not R₀. R₀ is the initial value before you undertake intervention.) This Lancet paper about post-relaxation China describes exactly that. Well worth a read. The time-varying estimates of Rₜ are particularly interesting, and low.

https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30746-7/fulltext

"Thus, proactively striking a balance between resuming economic activities and keeping Rₜ below 1 is likely to be the optimal strategy..."

"In the conventional framework of inferring Rₜ from epidemic curve data (as we have done), the lead time between actual changes in Rₜ and the detection of such changes is roughly equal to the sum of the incubation period and reporting delay..."

...So might be a bit slow. But we've observed here that the lag is only about 8 days (5 days incubation plus three days to detect). That might be tolerable if apply a big enough factor of safety to the clearance between the target Rₜ and 1.0.

I estimate the current Rₜ in Australia to be about 0.4, so there's quite a lot of space available. Also, our big reductions in Rₜ appear to have come from ending very large social gatherings (football!) and closing pubs and clubs, *not* from our later, more extreme lockdown.

As with any application of the observational management, best change one thing at a time, and not by too much. Then wait and watch before trying another.

Except, as have written before, there is another strategy: target effective eradication. On our current trajectory we're only about 5 weeks away from new cases becoming sporadic (one every other day happens about mid May).

At that point, if isolate each one, and track and quarantine all their contacts (or their whole local community), have killed it. Then no longer matters what your Rₜ is.

(Would need very strict border quarantine indefinitely of course, but so would a controlled Rₜ strategy.)