<

Category: Personal

Tags: #covid-19 #social-isolation

Published: 2020-03-28

# Covid 19 R Naught

Tags: #covid-19 #social-isolation

Published: 2020-03-28

The study of infectious diseases uses something called the Basic Reproduction Number ( R-naught/R0 ) to indicate how contagious a given infection is. It represents the average number of infections that one infected person will cause. Here are some examples of R0 numbers for known diseases (pulled from Wikipedia):

- Flu: 0.9 - 2.1
- Covid 19: 1.4 - 3.9
- Aids: 2 - 5
- Measles: 12 - 18 (yay vaccines!)

An R0 < 1 means that the disease will eventually disappear as it does not have a sustainable infection rate. The greater the number, the higher the contagion rate (I mean, come on Measles.. overachieve much?).

From what I can gather, the current average R0 for Covid 19 is 2.2 (hence my n^2 example). The easiest way to visualize it is, for every 10 people who have the disease, 22 more people will be infected by them. When comparing to the current infection rates, keep in mind that this is a statistical indicator and only deals in averages. Rural areas will have a much lower infection rate than densely populated urban areas. For example, North Dakota currently has 1 documented case while New York has almost 50k. (If you live in a densely populated area and are ignorant/arrogant, you WILL get sick.. science.)

The question I've been getting is, "what the hell is this whole flattening the curve thing?". The chart for infections over time is currently on an exponential growth curve (the front side of a bell curve). As a society practicing social isolation, we are now deep in the "deliberate intervention" stage. This will dramatically affect the growth (trust me), initially slowing to a logarithmic curve (the top of the bell curve) then seeing a decline (the backside of the bell curve). So, the curve being flattened means that the actual infection rate (not the statistical R0) starts to approach 1. Meaning, we have controlled our environment in such a way that 1 person will only infect one other person. The backside of the bell curve happens when the actual infection rate drops below 1. The question we all have right now is, how long will that take? Using the basic idea of 14 as the number of days one person can be contagious (we'll call this the infection cycle), and taking into account people not knowing they were infected and infecting other people in their household, it seems logical that we will have to endure about 2 infection cycles before we start to see the logarithmic trend we are all hoping for. So, as of right now, my guess is 2-3 more weeks minimum.

We are all now patiently waiting for what is known as a lagging indicator to validate our efforts but, in the meantime know this:

You are doing the right thing and it WILL have a significant effect on the infection rate.

Stay home. Stay healthy. Stay positive.

Oh, and knock it off with the toilet paper you dipshits.