Coronavirus : Update 16 from the Epicenter

Posted by in Coronavirus

Here are the charts that tell you if it’s safe to end the lockdown in your area

OK, so we’re going to change it up a little for this update. Yesterday I spotted that Kevin Systrom (one of the Instagram founders) had launched a new website that is tracking the Rt of COVID-19 in US States in realtime. I’ll let him describe Rt in his own words :

In any epidemic, π‘…𝑑 is the measure known as the effective reproduction number. It’s the number of people who become infected per infectious person at time π‘‘. The most well-known version of this number is the basic reproduction number: π‘…0 when π‘‘=0. However, π‘…0 is a single measure that does not adapt with changes in behavior and restrictions. As a pandemic evolves, increasing restrictions (or potential releasing of restrictions) changes π‘…𝑑. Knowing the current π‘…𝑑 is essential. When π‘…≫1, the pandemic will spread through a large part of the population. If π‘…𝑑<1, the pandemic will slow quickly before it has a chance to infect many people. The lower the π‘…𝑑: the more manageable the situation. In general, any π‘…𝑑<1 means things are under control. The value of π‘…𝑑 helps us in two ways. (1) It helps us understand how effective our measures have been controlling an outbreak and (2) it gives us vital information about whether we should increase or reduce restrictions based on our competing goals of economic prosperity and human safety. Well-respected epidemiologists argue that tracking π‘…𝑑 is the only way to manage through this crisis. Yet, today, we don’t yet use π‘…𝑑 in this way. In fact, the only real-time measure I’ve seen has been for Hong Kong. More importantly, it is not useful to understand π‘…𝑑 at a national level. Instead, to manage this crisis effectively, we need a local (state, county and/or city) granularity of π‘…𝑑.

Kevin Systrom

If you’re in the US, then I strongly advise you to check out his website, as it is as beautiful and functional as you would expect, with each state given its own Rt chart and the whole country laid out in a swoosh :

Kevin also published the python code behind the charts on Github, where it was forked by a chap called Nicolas Weiner and altered to use country-level data from Here are his graphs of Rt for the countries we follow :

However, as Kevin points out in his introduction, numbers at this level are pretty pointless as the dynamics of the epidemic play out regionally, if not in individual cities and neighbourhoods.

I therefore forked his code πŸ™‚ and made versions for the Italian regions :

Rt progression for all Italian regions

If we zoom in on Liguria, where we live, it’s clear that we have been Rt < 1 and stable for several weeks, and there should be no hesitation from the regional government to initiate a controlled lifting of the lockdown :

Here are some of the States in the US where friends and family live. Let me know if you’d like one adding, but your best bet may be to head over to Kevin’s official site :

Rt progression for selected US States

I’m working on getting the data set for UK counties, and will publish them when they’re ready.