Exponential growth and the worst case scenario

I wrote this post for a Facebook audience, and I may have skimped on technical accuracy for clarity of my main point.
DON’T PANIC - not yet - this is a WORST CASE scenario assuming we do nothing to prevent COVID-19 from spreading. We are already doing something, so that worst case shouldn’t happen. I hope.

Best case scenario as of today is about 200,000 dead. Still awful, but about 8 times less than 1.7 million. Which is why I wanted to write about exponential growth.

When a disease first spreads in the population it starts off slowly. Only a few people have the disease, and only a few more are usually exposed to it at a time. But as more people become infected the number of new infections increases too. There is a number known as “exponential doubling time” which gives the rate of increase in terms of the length of time in which we expect the number of cases to double.

The difference between the best and worst case scenarios I mentioned before is roughly a multiple of 8. That’s that same difference we expect from three doubling times (2 times 2 times 2 equals 8). Earlier today my friend Kevin McCarthy mentioned an informal estimate of the current doubling time as 2-3 days. Using that estimate we can approximate the difference between best and worst case scenarios as 6-9 days - a week, maybe two if I round up.

The point is that during a period of exponential disease growth LITTLE THINGS MATTER. Slowing the disease even a little bit NOW, can make a huge difference in the number of cases, and number of deaths, LATER. Things we do now to prevent the spread of COVID-19, even little things, matter a whole lot.

One more thing. Today I see more people than ever engaging in pointless political or religious argument, lashing out at each other when what we really ought to be doing is coming together for mutual support. I get it - people are scared, and scared people lash out. I want to lash out too, but it doesn’t help. I hope that instead of fighting, maybe we can be supportive of the health care workers, service workers, and all the other helping to keep things going while we wait this out. Maybe we can support each other a bit more too, because even sheltering at home means you are doing something important.

Stay home, stay healthy, help keep that worst case scenario from happining.

Or come stalk me on FB :grinning:

Today’s numbers offer some hope, registering the first declines in over a week, both for daily cases and daily deaths, globally and USA. If March 28 turns out to be the worst day and the decline is symmetrical, with better fortune, and a doomed economy, we could be under 80,000 fatalities.

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