Carl Hennigan

There's 30-fold variation in countries' case fatality rates.

And that's basically the measure of the number of deaths

of those with detected disease.

And we basically say that measure is pretty useless.

On the basis, it's a function of testing and who you test.

And as you test more people, your case fatality rate will go down.

If you test just severe people, selection bias, it will go up.

And all of these features have happened.

In fact, in Italy, it doubled in a week, the case fatality rate.

So we basically are saying that's not a helpful measure.

What would be really helpful is to fix on some measures.

So, for instance, you can have symptomatic hospital fatality rate.

That's very helpful.

And every country could have reported that in the same way.

So if you get admitted to hospital with symptoms, what's the fatality rate?

And then you could have compared country to country.

But as it stands, case fatality rates are a waste of time.

And we look at them and they do what they always do in this situation is they continue to trend down and down and down.

And they'll get nearer and nearer to the truth, but with some way off that yet.

I think we continue to make the same mistakes again and again.