People are used to seeing graphs (plots) of Y vs. X: temperature vs. day of the week; or GDP vs. year. Given that training, why are plots of COVID-19 so hard to grasp? I think I observed something that may help to understand this difficulty.
Let us have a “gedanken” pandemic. Let us suppose that a disease breaks out that has a doubling time of 9 days. So, on day 0 we have one patient, and every 9 days we end up with twice the number we had before. After a full 10 weeks, we would have seen fewer than 250 patients. Looking at the plot below, I see that, while things are accelerating, all I have to do is “lift my foot off the pedal” and things will calm down. Seems like something I’ve seen before.
Now, let’s wait for 10 more weeks. We see:
Here’s my observation: the world of 10 weeks ago is unrecognizable. This feels true. Think back to March. Can you remember what life was like before COVID? For me, not really. How different was the daily news broadcast in April? Exponential growth has created a world that didn’t exist 10 weeks ago.
The same effect occurs with respect to resources to cope with the pandemic. Suppose we can provide beds for 10000 COVID patients.
Even at week 15, we’ve got more than 3 times the number of beds (the red line) that we need (the blue line).
Now, wait 5 weeks.
Our capability has been crushed.
Should we have capacity of 50000 beds? At week 15, with 3300 cases, that would have seemed ridiculous and wasteful. But wait two more weeks:
Our ridiculous over-planning has been crushed just as easily.
There are two other destructive phenomena that involve exponential growth: a plague of locusts, and nuclear weapons. In all these cases, even unreasonable expectations of the world are destroyed by reality.
It is said that people will get used to what COVID does. I claim, not. I claim the opposite: people will be repetitively stunned by what happens.
The only way to prevent any of this is to prevent exponential growth. Right now (21 July), the USA is failing to do that.
A word about how I’ve plotted things: I made the time axis occupy the same space on the page no matter its actual duration. That may be thought of as a cheat. But not if you consider that we’re trying to understand an “event” like COVID-19. The takeaway, to me, from above, is that the “event” breaks apart into “now” vs. “forever ago”: the past three weeks are a brand new bad world, and the next 3 weeks will be shockingly, unimaginably worse.
The doubling time of 9 days is short by present standards. But periods of such growth have existed and could again. It is not impossibly quick.
Eventually, we would run out of people to get sick. But right now slightly over 1% of the US population has been sick. That leaves almost 99% available to get sick: approximately an unlimited supply.
Can you imagine the present situation being 10 times worse? Or just 3 times worse (Florida would have 60000 in the hospital and 15000 dead)? No, you can’t. We have no other option than to slow, stop, and finally reverse the growth.
