The other day, I posted about the mathematics of coronavirus spread. I used extrapolation to make an estimate about the number of potential cases in the state.
It was using a few assumptions, but since we knew the assumptions, we were able to keep the final number – about 100 – in context.
This time, it will be a bit different. Because it looks like the Coronavirus is growing exponentially across the globe now.
….. oh pic.twitter.com/NZtmWi0yh1
— Nick Lilja (@NickLilja) March 17, 2020
What does that mean? I’m so glad you asked.
Exponential growth
A lot of people probably remember taking algebra class, but not a lot from it. That’s understandable. While math can be a lot of fun, I know that for some, it can also be stressful and annoying.
It was stressful and annoying for me until I was about 22 and it clicked. I took a statistics class. and I understood it. And from there, it is like it unlocked something in my brain where all the sudden I “got” math
But I’m going to try to break it down and make it digestible.
The idea is that if you ran the equation, e^x, it explains exponential growth. And exponential growth is all about doubling, in a sense. It turns out, e is equal to 2.71 (and a bunch more numbers, but check out the video below for an explanation). So, for example, e^1 = 2.71 but e^2 = 7.38 and e^3 20.38 so you could pick a line on the X-axis for each value, 1, 2, 3 and the value for y would be 2.71, 7.38 and 20.38
This was always the concern with Coronavirus. Since the R0 value (we talked about this the other day) is between 2 and 3. It means that one sick person will transmit it to two or three other people. And that lines up really close with the value for e. Which means if the virus went unchecked and was allowed to freely transmit between people – without social distancing and quarantine, it could grow – potentially – exponentially. Doubling every next day.
And there have been place in the United States where that has happened. Louisiana, for example has come pretty close. They went from 3 to 136 positive cases in about 5 days. And e^5 = 148. So, it is close.
And 2-percent of 136 is 2.72. And there have been three deaths. So, sadly, the mortality rate is holding in Louisiana.
Okay, Nick, but how does that help us?
Good question! It already has. Since we have a graph of global growth that matches close to e^x and we have an example of close to e^x growth at a location in the United States, that is why you’re seeing a lot of governmental authorities ramp up messages of social distancing, isolation, and quarantine. Because the scientists and doctors, and hopefully mathematicians, are telling the People In Power that we are sliding down (or in this case, up) a very slippery slope.
This is no longer about “how bad will it be tomorrow?” because we know where the line goes! Without intervention in Louisiana, the number, on Wednesday, could be around 400.
Now, in this case, testing becomes the limiting factor. If there aren’t 400 cases tomorrow, it isn’t likely the lack of new positive cases as much as it is they may not be able to test 400 people in a day.
Like I said the other day, at some point this whole thing will change from a medical transmission problem to a math problem about transmission. And it looks like it is getting pretty close to the latter.
Unless we change our habits. Hand washing can only do so much. Especially if we are all hanging out at a bar sharing drinks and high-fiving while watching a game.
This is like a tornado, you’re in the polygon
Karrie, our main anchor, came up with a great analogy tonight while we were chatting out how this virus seems to put some on their deathbed and others have just a cough and a fever. I’ve heard stories of perfectly healthy 20-somethings being knocked off their feet by this thing. And I’ve seen reports of 55-year-olds that get a cough and move on with life. I have a friend (out of state) that is getting tested tomorrow because he has a fever and a very tight chest – but that is it.
The level of sickness from the virus is unpredictable because it is so new. It is like severe weather.
Think of this as tornado. On ground. And you are in the polygon. And it is headed for your neighborhood.
There is a chance that it goes through your neighborhood, and your house is the one that gets spared (you get it, but aren’t really that sick). There is also a chance it tears your carport off and spares your house (okay, you get a fever and a cough, but you’re okay). And there is also a chance that it rips the roof off and all that is left is a slab (it knocks you out with a bad fever and puts you in the ER).
But no one knows what will happen, exactly. Because no two tornadoes are the same. Just like this sickness.
There are those in the higher risk group. Those with diabetes, lung disease and heart disease. These are the people in trailers, RVs and mobile homes. Only, in this case, they can’t “leave” their “at risk.”
There are people in a lower-risk group. Those that are younger. But they aren’t completely immune, either.
Sounds scary, right?
But there is a BIG difference. In this case WE control where the tornado goes. We control it by practicing good social distancing, washing our hands and not interacting with older folks if we have been in contact with people who are sick – or those who we think may have been in contact with someone who was sick.
We can help guide the tornado away from the “At risk” group. And you can even help guide the tornado away from YOUR house, too, by following the steps from the CDC that I discussed Monday morning.
Based on the numbers, you can see that a lot of people are going to still get “hit” by this, but you don’t have to be one of them.
So respect the (medical) polygon. We are all in it. Right now. And do so by practicing social distancing, washing your hands, and avoiding public places and people who may be sick.
You do all the right things, and things will turn out okay.
