It’s a losing position. Biology tells us, among other things, that the species best suited to their environment will have the best reproductive success. When the version of this particular coronavirus which we’ve labeled CoV-2 evolved a spike protein that happened to fit nicely into the ACE-2 receptor in human cells, it became an evolutionary winner. It had phenomenal reproductive success in part because the human immune system had never seen this particular pathogen before. The environment that is the human body suited CoV-2 perfectly, so it had wonderful reproductive success. The human respiratory pattern was also a great pollinator for it, spraying it around with every breath. There are lots and lots of humans on the planet, and we tend to bunch up together in groups and we like physical closeness, talking, laughing, singing and generally doing a lot of breathing. CoV-2 was perfectly adapted to take reproductive advantage of this environment.
Viral contagions are classified by something called their R 0, or R-nought. This is their reproductive rate, which tells us how infectious they are by applying some math to the likely rate of infection from one host to another. If the R is greater than 1, that means the virus will be able to spread in a susceptible population, because each infected person will infect more than 1 other person. The larger the R-nought, the harder to contain the spread. Measles for example, has an R-nought of roughly 15. Every infected person will infect 15 others in a susceptible population. That makes measles very bad indeed. CoV-2 being the evolutionary winner that it is, has an R-nought around 2.5. That makes it sound less bad than measles, which is true, except for the issue of a susceptible population. We’ve done a pretty good job of shrinking the susceptible population to measles by vaccinations which recognize the measles virus, and effectively prevent it from making a home inside our bodies. No such thing exists for CoV-2. So there are lots and lots of susceptible people for CoV-2 to spread to.
Now an R of 2.5 doesn’t sound that bad, since 2.5 isn’t much bigger than 1. But that’s where the math of exponential growth comes in, which our brains didn’t evolve to perceive very well. It takes some effort to fully grasp the concept, so let’s delve. If 1 infected person breathes their viral containing droplets around in a small group of friends, it’s likely that 2.5 of that person’s friends will give CoV-2 a new home to reproduce in. Let’s round up to 3 to make it easier. Those 3 infected folks now go to a movie theater and breathe their infected breath for a couple of hours to a crowd of susceptible humans. Each of them will infect 3 more. So from that 1 original infected person, we now have 13 infected folks. They go home and infect their roommates or loved ones they live with, who then go to work the next day and infect 3 people each in their offices. In a matter of a couple of days, the 1 infected person has now caused 135 or so infected humans. Then they tell 3 friends, who then tell their 3 friends, and so on. Outbreak.
It’s what makes self isolation and stay at home orders so effective at slowing the spread of the virus. By not hanging around each other, the virus can’t keep pollinating the populace. It’s biology and math. Unfortunately, some people look at probabilities and fail to see the risks. Let’s look at an example of what I mean by that.
In my little zip code there are 50 reported cases of COVID-19, the disease caused by the CoV-2 virus. The Dept of Health estimates there are probably 357 cases in the zip code based on some basic probabilities and the likely R-nought of CoV-2. There are roughly 44,000 residents in my little zip code, so that means that less than 1% of the populace has been infected. That gives people a sense of relief because they think their risk is low, since so few people have it. However, there are 43,643 people at risk of getting infected. The risk exists because of the biology. CoV-2 is easily transmitted as we’ve discussed, and humans are a perfect home for it. So all of us are at risk. What we should look at is the probability of infection vs. the risk of infection. The risk is high, but the probability can be seen as low due to the small number of known infected people. However, the infected people, particularly those in the early stages of infection who don’t have any symptoms, are freely moving about. They go out to eat, they go to stores, they stand in crowds, and they pollinate the rest of us, who as mentioned, are at high risk of infection because of the biology.
The risk actually decreases as more people get infected. Assuming our bodies are able to fight off the disease and rid ourselves of the virus, we should develop immunity to it to help us kill it more effectively if we’re exposed again. This isn’t known for sure yet, but that tends to be the pattern with viral contagions. We may never be able to completely avoid getting ill from inhaling a bunch of CoV-2, but perhaps we can get a better immune response after having been exposed to it before, and kill it more effectively in the body. In time, it may produce much weaker symptoms, like the common cold, many of which are caused by coronaviruses.
So right now, the fact that 99% of the populace is at high risk of getting infected by the evolutionary marvel called CoV-2 means we should all be taking precautions. It doesn’t matter if a particular political leader says please go out and spend money. It doesn’t matter if your friends say it’s no big deal since so few people have it. It doesn’t matter if you are dying to go out and sing karaoke or grind up against someone on a crowded dance floor. CoV-2 exists, it’s everywhere on the planet, and it is very effective at reproducing inside your body. The biology is on its side. So is the math. One sick person in that restaurant with you will probably get you infected along with 2 more of your friends. And you’ll have a few days where you feel fine to keep going out and infecting more people, who will then feel fine for a few days and go out and infect more. The biology and math are not in our favor. Do yourself and your fellow humans a favor and don’t argue against biology and math.
- Keep your distance from people.
- Wear a mask in public, especially indoors.
- Avoid large gatherings, again, especially indoors.
- If you’re sick at all, stay home.
- In fact, stay home as much as you can.
Eventually, we may get a safe vaccine that will help us either kill CoV-2 when it enters our body before it can reproduce, or will at least make it reproduce less effectively. Lots of brilliant minds are working on it right now. We may develop effective treatments for it, so that when we do get sick, we can limit the damage from COVID-19. Viral pneumonia is no picnic. But until that day comes, it’s up to us. Each of us.
PS I’m not an expert in biology or math. This post is very, very basic. But basic is probably good enough to keep you relatively safe.
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