Wednesday 18 March 2020

Covid-19, lightning strikes, and the nature of risk.

There's this way of measuring risk that's so popular it's a cliche: "You're more likely to be struck by lightning than [insert supposedly unlikely event here]." It's interesting that we're hearing it used less these days about terrorist attacks — in the UK, you have actually been more likely to be hurt by a terrorist than by lightning for some years now, and perhaps, even without looking up the figures, people are intuitively sensing that. That rather annoying thought aside, what I really want to discuss here is the fact that the comparison is a big steaming pile of fallacy.

Because the way the expression is used is always to express derision at the very idea that anyone might worry about such a tiny risk. The logic goes:

The probability of X is lower than the probability of being hit by lightning;
the probability of being hit by lightning is extremely low
: therefore taking measures to avoid X is a stupid waste of time.

But here's the thing. In the Developed World, every tall building has a lightning conductor on top, and so do most of the smaller ones. And every crane. Every car has been designed to protect its occupants in the event of a lightning strike. Aeroplanes are designed to survive lightning strikes. The electrical ring main in your house is lightning-proof. The entire national electricity grid has lightning resilience built in. Scientists and engineers keep researching lightning, so that we can keep improving our lightning-proofing measures. And we teach our children not to shelter under trees in thunderstorms. Apart from that last one, this all costs money — money and time and resources and effort. Our entire society is, at great expense, largely lightning-proof. The reason we've done this is obviously not because it's such a rare event that it's not worth doing anything about.

So the logic is actually:

The probability of X is lower than the probability of being hit by lightning;
the probability of being hit by lightning is high enough that we collectively spend billions on mitigation measures against it
: therefore taking measures to avoid X is a stupid waste of time.

It's even rarer than a thing that isn't rare!

I am reminded of this by the scaremongermongering fuckwits out there still, even now, saying that Covid-19 is not much worse than the flu.

Influenza is a big deal. We research the new strains constantly, so that we can identify which are the ones we need to vaccinate against each season. We develop a new vaccine for those strains every year. We deploy that vaccine to millions of people. We prepare a certain amount of capacity in our hospitals to deal with serious flu cases. We train doctors and nurses in its treatment. We obviously do not do all this because flu is not worth doing anything about.

Again, here's that logic, only even worse this time:

Covid-19 is not much worse than the flu;
the flu is a serious enough problem that we pour massive resources into combatting it
: therefore making all this fuss about Covid-19 is stupid.

It's only slightly more dangerous than a very dangerous thing! Genius.

Part of the problem here is the word "fuss" and its various synonyms — "worry", "panic", etc. These are loaded words, all being used to mean "effort", but with derision of that effort built in. It's true: we don't make a lot of fuss about flu; we don't worry or panic about flu; but we do put lots of effort into fighting it. We just don't think of that effort as fuss or worry or panic, because it's routine. But it's still effort, and using loaded words doesn't create some logical difference between that effort and the effort put into fighting Covid-19.

And of course the other glaringly obvious point is that we aren't replacing flu with Covid-19. We're getting both. This is a new risk piled on top of all the old existing risks we already know about. Very few people do think about the risk of dying of flu — or tuberculosis or hantavirus or an embolism or a car crash or a freak shopping-trolley accident (it happens). What we do think about and take into account in the back of our minds is the risk of dying in general. That risk just suddenly increased, so of course we're seeing an adjustment. And it's not surprising or irrational that that adjustment is so extreme when the size of the risk is currently unknown and unknowable.

Now, there is an argument to be made that, whilst Covid-19 just increased the risk of dying, we have, on the other hand, been steadily decreasing the risk of dying for the last few decades, and so we might rationally offset those two factors: sure, things just got significantly more dangerous, but cancer is no longer a death sentence, you can live a long life with HIV now, and modern seatbelts and airbags are frankly amazing, so maybe this stuff balances out. Thus far, I have heard that reasonable argument from precisely zero people.

And then there's the fatality rate. The scaremongermongers measure Covid-19's badness by its fatality rate, with the underlying assumption, sometimes implicit, sometimes explicit, that those who don't die will be just fine. Sorry, but no. There's a whole world of mostly horrible grey areas between dying and being AOK. Covid-19 causes pneumonia. Pneumonia is nasty. It's very painful. It damages your lungs, usually long-term, often for decades, often permanently. "Recovering" from pneumonia could well mean that every respiratory illness you get for the rest of your life will hit you harder than it would have otherwise — and there are a lot of respiratory illnesses out there. Imagine if, every time you caught a common cold, it turned into a chest infection. Imagine if you got so many chest infections, you built up a resistance to most antibiotics. That's what a significant proportion of survivors are facing. And then some lucky sods can carry Covid-19 completely asymptomatically. It's not all that bad for everyone, but it's a lot more complicated and worse than just putting survival in the "no problem" column.

Another thing you've no doubt been hearing is that Covid-19 mainly kills elderly people. This is true, and, not to be callous, but, frankly, after a certain age, whatever you die of, you really die of old age. When she was merely in late middle-age, my grandmother broke her leg and didn't notice, continuing her daily ten-mile walks across the Yorkshire Moors while being vaguely annoyed that the limp wasn't wearing off. In her nineties, she broke her leg and, though it took a year, died. We know this is how life goes, and are generally resigned to it. But perhaps you haven't fully thought through what "elderly" means in the context of Covid-19 fatalities.

You don't suddenly drive off a statistical cliff-edge at the age of seventy. There's a curve. Yes, at seventy, you're at much higher risk. At sixty, not as bad, but still higher risk than a fifty-year-old. And so on. I'm forty-five. I certainly don't think of myself as elderly. But I'm on the curve. I'm unlikely to get away from Covid-19 as cleanly as a twenty-year-old would. I run part of that increased risk that shows up in the stats and gets described with the shorthand term "elderly". Maybe you do too.

I'm not panicking about this. I half hope I catch the damn thing, so I can grow some antibodies and cease to be a danger to my wife. But only half, as it will probably be fucking agony. But this is not panic, it is not fuss, it is not a ridiculous overreaction to nothing much: it is a reasonable response to a rational analysis of something that really is much worse than flu.

1 comment:

Unknown said...

Thank you. I check in periodically and always enjoy your musings.

I would be interested to read a follow up now that more data is available. I do wonder whether the measures taken to lower the risks associated with covid have been counterbalanced by various increased risks; missed hospital appointments, mental health etc. etc.

Trust you're well,