Thursday, April 2, 2020

More Coronavirus Guesswork

As I said before, you really ought to talk to an epidemiologist about what to expect now…

But since I can’t help thinking about the possibilities myself, I’ll just go ahead and lay out some of my guesses here.
 
The first thing to note is this – we have no idea what the scope of the problem is, largely because we haven’t been testing nearly enough.  As South Korea has shown, a large group of carriers don’t show any symptoms at all, so they can spread COVID-19 without being aware that they’re doing so.

If we had locked down the relevant states as soon as they’d had a case of ‘community spread’, and then tested the s*** out of everybody, we might have been able to get ahead of the transmission chain (once we’d lost track of it enough to get community spread in the first place), and perhaps could have limited where we needed to shelter in place.

But that ship has sailed, it’s water under the bridge, <insert cliché making the point that it’s got nothing to do with today’s problems. Mostly because it has now spread far enough and wide enough that there’s almost no hope of limiting it to a few ‘known hotspots’>

We have no idea of the scope of the problem.

However… There are ways of trying to get an estimate of it. In particular, if the mortality rate is actually fairly consistent (taking into account demographics like age and obesity, as well as increased mortality when hospitals are overwhelmed) then we can make a few educated assumptions.

Namely that South Korea, which did test the s*** out of everyone, has the most reliable data. That is, if their mortality rate is .6 or .7%, then you can argue that most other nations have a similar rate… and it only looks higher because we’re not testing enough to catch everyone. (That’s why I used their rates in my best of the worst case scenario earlier).  It’s not an exact measurement, of course, for all the reasons I listed above, and more. That is, in addition to demographic differences and healthcare resource availability, some people may be dying of the coronavirus without being counted. It’s just designated ‘pneumonia’, or ‘flu’.

Still, I’m just running the numbers to get some sense of scale, not to make a 100% accurate prediction. So let’s roll with it…
 
Currently, as of 2 Apr 2010, we have about 5000 deaths from COVID-19. If we take South Korea’s rate of .6%, then we can calculate how many people are likely to be infected:
 
If 5000/x = .006, then 5000/.006 = x, which is ~833,333 people. (It’s math. You can also say 5000/x = 6/1000; so 5000*1000 = 6x, so 5,000,000 = 6x, so 5,000,000/6 = x… all of which still comes to 833,333 people.)
 
In other words, we probably have around 800 thousand people who have been infected with COVID-19, even though we’ve only tested enough to confirm 215,000 of them.
 
The other thing worth noting, is that if it really takes around two weeks for people to show symptoms, then what this really is saying is that two weeks ago we had 800,000 people infected with COVID-19. There’s various discussions on what the rate of infection is, and when we double, but some of that is also tied in with the utter lack of testing, and the growth in positive cases as we’ve started rolling out more tests, so who the heck really knows? Let’s just say, for the sake of assumption, that the rate of infection normally doubles every week. The confirmed cases are more like doubling every two or three days, but that could be because of all the issues I listed. In the interests of another best/worse type scenario, I’ll just go with ‘doubles every week’.
 
That means we could actually have 1.6 million or even 3.2 million people who have been infected already.
 
Now, this is where the guesswork really comes in to play. Because of course most of the cases started at places where we have travelers from other infected areas (airports, seaports… and it’s no surprise that most of the cases started it places like Washington state, California, New York… and Chicago.)
 
 
So where are those 1.6 million or so infected people? By now, pretty much everywhere.
 
Oh, it’s probably still primarily in urban areas. But I live in a town of around 230,000 people and as of today we have 38 confirmed cases. Granted, we’re a university town that probably has quite a bit of direct travel to Chicago (and overseas), so maybe that’s not much of a surprise? We’re probably a couple of weeks behind Chicago in terms of the timeline, and thanks to our governor and mayor we enacted countermeasures early enough that I’m hopeful it won’t get too bad.
 
Because you have to figure that all the nearby, more rural, smaller towns? There’s probably people from there that come in to the ‘big city’ for one reason or another. And they definitely have a better chance of NOT catching COVID-19 now that we’re limiting how much we’re out and about.
 
Again, I don’t have any real numbers on how fast this thing spreads. You def. want to talk to a professional on that. But it makes sense to me that we would see spread from areas (like Seattle, or Chicago) out into the smaller towns, and eventually even into places like North Judson, Indiana (which has all of 1,739 people.) We’ve had a month of community spread, so whether it’s already done that or not depends on all the various factors I keep saying you should talk to an expert on.
 
What we can say for sure is that the actions we all, as well as our state governors have (or have not) taken, will play a big role in how fast that happens.
 
I came across another article on social media, from an epidemiologist, discussing what’s likely to happen next. I don’t recall all of it, but he made a point about how some of our actions impacts the success (or failure) in reducing transmission.

He pointed out that each family acts like a single unit, so if one of your kids has a play date with another… it’s as though your entire family has interacted with that entire family, and if they’ve had a play date with another kid, then that entire family has also interacted with theirs… and with yours when you do your play date.
 
In other words, if people are still meeting up with each other – even if it’s in smaller groups – the virus is still going to spread. It’s just going to spread through smaller networks. And, perhaps, at a slower rate (if the kids normally play together at school every day, and it took three days to set a play date, that’s a three day delay in transmission.)
 
As people have been saying, what good is it to tell everyone that schools are closed and they have to work from home, if they still schedule a play date or go out to dinner with a couple of friends or (for the highest chance of mass infection) still go to church?
 
A month, maybe two, of community spread. And it’s already spread to medium/small sized cities like mine.

Which means in the next month or two I think we’ll really start to see the impact of our collective decisions on social (or really, physical) distancing.

No comments:

Post a Comment