Incubation Period + Spreading

Some good news…

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The biggest problem with CoronaVirus is that it is spread by people who don’t know they have it. So how long is that?

According to one study, it takes on average 6 days from date you are infected to when you start to develop a fever. By 11 days, 97% of those infected have symptoms. On day 17, if you are unhealthy, you die.

It’s likely that most of the spreading happens in those 6 days. Let’s take as a hypothesis that the spreading rate is 25% per day (an educated guess) and see where that gets us. After 6 days, the virus population is 1.25⁶=3.81 people. In other words, the new infected number R⁰=2.81. This is “in line” (maybe a bit high) with other estimates. Let’s just round it up to 3.

So here’s the rough model:

  • unsuspecting carrier acquires the virus

Turnarounds can happen fast!

Whether you lockdown as Italy is doing, or aggressively test and track every new case (testing every person in contact with that person), the examples of China and South Korea show that this can be tackled and it can be tackled quickly.

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In the case of Korea, agressive measures were taken end of Feb (when total cases were around 4K, where the US is today) and the “curve bent” on Mar 05, after the 6 day incubation period, flattening out dramatically on March 10, 11 days into the incubation!

The case of Italy

Italy instituted dramatic controls to separate people in the Lombardy region on March 10, 2020 and on all of Italy on March 13, 2020. The numbers are still trending up (as you might expect). The real question is do we see a dip on the numbers starting Thursday March 19 (6 days after lockdown). I am guessing we do, with a dramatic decrease on Tuesday March 24 (11 days after lockdown).

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What does that mean for the US?

Depending on the measures taken in the next 7 days, we have a decent shot of “bending the curve” and flattening things out in the next 2 weeks. It’s definitely possible that we “get through the worst of this” in April, with a flattening curve.

I’m happy that the media has finally scared the average American into taking this somewhat seriously. Hopefully, like Italy, we enact severe penalties for walking around infected, just in case people have the bright idea of putting the rest of the population at risk.

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