Folks who have never studied mathematics, or engineering, or the sciences almost always tend to view the physical world as though it were a collection of linear functions: add twice as many logs to the fire, and you'll get twice as much heat; triple the amount of ingredients shown in the waffle recipe, and you'll get three times as many waffles.
It always comes as a shock to young drivers when I explain to them that the impact energy from a 60 mph collision with a tree isn't three times as much as a 20 mph collision... it's 9 times as much. (i.e., much of the physical world is ruled by polynomial functions)
It is in these early days of the current pandemic that I am discovering just how many people truly don't have a grasp of exponential functions.
For the zillionth time, I have heard people comparing the R0 of SARS-CoV-2 (about 2.4) to the R0 of typical Influenza-A (about 1.4). The assessment I hear is consistently that "2.4 really isn't much higher than 1.4".
Assuming we start with 1 infected patient, after 20 "infection generations" at an R0 of 1.4 we end up with about 3,000 infected patients.
Under identical circumstances with an R0 of 2.4, we end up with about 69,000,000 infected patients.
Neither of those numbers is a typo.
I suspect I'm largely preaching to the choir (again), but I hope it's obvious how critically important social distancing is going to be in ratcheting that R0 down to something manageable.
Almost all of us have parents or grandparents or folks with asthma or immunocompromised loved ones. It's worthwhile to try to persuade our sceptical friends and acquaintances of the importance of avoiding large gatherings. It's important that we do this now, even in communities that don't yet have cases. (By the time you see the first case, the virus has already moved on.)
I've been generally avoiding mainstream media, preferring instead to read relevant journals and epidemiologists. Here's a good paper in The Lancet on just how critical "flattening the curve" is going to be.
How will country-based mitigation measures influence the course of the COVID-19 epidemic?
