A lot of people in the UK are naturally asking, how long will the Corona Virus shut down last? For an answer we can look to South Korea.

One chart explains all. It comes from the widely referenced graphs in an analysis on medium.com titled “Coronavirus: The Hammer and the Dance” by the engineer-entrepreneur Thomas Pueyo. The article is very long, so consider this a precis.

“Strong coronavirus measures today should only last a few weeks, there shouldn’t be a big peak of infections afterwards, and it can all be done for a reasonable cost to society, saving millions of lives along the way,” Pueyo writes.

“If we don’t take these measures, tens of millions will be infected, many will die, along with anybody else that requires intensive care, because the health care system will have collapsed. … Every single day we delay the coronavirus, we can get better prepared.”

South Korea had the worst epidemic outside of China. Now, it’s largely under control. They achieved this mostly with aggressive testing, contact tracing, and enforced quarantines and isolations.

South Korea was prepared, with stronger epidemiological authority, education on hygiene and social distancing, and early detection and isolation. It didn’t have to pay with heavier measures afterwards.

 

The hammer and the dance

But Western countries have not been so far sighted. In the case of the UK, it has been been playing catch up with a series of serious measures designed to control the rise of new infections. We can call this suppression strategy of social distancing and lock-ins “the Hammer.”

This strategy can definitely control the outbreak within up to seven weeks if everyone abides by the rules. (France has already talked of extending its “hammer” restrictions to mid May for examples.)

Once the Hammer is in place and the outbreak is controlled, writes Thomas Pueyo, the second phase begins: the Dance.

The Dance describes the longer-term effort to keep this virus contained until there’s a vaccine. It looks like this.

Depending on how cases evolve, we will need to tighten up social distancing measures or we will be able to release them. That is the dance of R (R is the transmission rate). You can think of it as a dance of measures between getting our lives back on track and spreading the disease, one of economy vs. healthcare.

Early on in a standard, unprepared country, the transmission rate is somewhere between 2 and 3: During the few weeks that somebody is infected, they infect between 2 and 3 other people on average.

 

R < 1

If R is above 1, infections grow exponentially into an epidemic. If it’s below 1, they die down.

During the Hammer, the goal is to get R as close to zero, as fast as possible, to quench the epidemic. In Wuhan, it is calculated that R was initially 3.9, and after the lockdown and centralized quarantine, it went down to 0.32.

But once you move into the Dance, you don’t need to do that anymore. You just need your R to stay below 1.

A lot of the social distancing measures have true, hard costs on people. They might lose their job, their business, their healthy habits. But you can remain below R=1 with a few simple measures.

This is what worked in South Korea:

• If people are massively tested, they can be identified even before they have symptoms. Quarantined, they can’t spread anything.
• If people are trained to identify their symptoms earlier, they reduce the number of days in blue, and hence their overall contagiousness
• If people are isolated as soon as they have symptoms, the contagions from the orange phase disappear.
• If people are educated about personal distance, mask-wearing, washing hands or disinfecting spaces, they spread less virus throughout the entire period.
• If with all these measures we’re still way above R=1, we need to reduce the average number of people that each person meets.

There are some very cheap ways to do that, like banning events with more than a certain number of people (eg, 50, 500), or asking people to work from home when they can.

Other are much, much more expensive economically, socially and ethically, such as closing schools and universities, asking everybody to stay home, or closing businesses.

Summary

During the Hammer period, politicians want to lower R as much as possible, through measures that remain tolerable for the population. In Hubei, they went all the way to 0.32. We might not need that: maybe just to 0.5 or 0.6.

But during the Dance of the R period, they want to hover as close to 1 as possible, while staying below it over the long term term.

That prevents a new outbreak, while eliminating the most drastic measures.

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