I heard a different way of looking at the mortality rate from one of the scientists involved with Coronavirus today. We are all aware that it seems to affect the elderly more than the young but that may not be quite what it seems. Whatever age you are there is a probability that you will die during that year. Suppose you are 50. If you take everybody who dies at the age of 50 in a year and divide by the total number of people who are 50 at that time you get the probability of dying at age 50. The same is true of every age. That probability increases with increasing age. You can now consider that the Covid-19 disease increases your probability of dying at that age over what it would have been if the disease hadn't appeared. When you look at it from that viewpoint it turns out that COVID-19 increases the probability of dying at any particular age by the same amount for all age groups. It doesn't really discriminate.

For simplicity lets say it doubles your probability of dying no matter how old you are. It isn't that big a factor but it doesn't matter, it still illustrates the principle. If you are 20, for example, you have a very low probability of dying in that year. Even if you double that probability it is still a very small probability so it looks like 20 year olds are not really affected. If you are 80, however, you have quite a high probability of dying in that year. If COVID-19 doubles that probability it has an enormous effect.

Warwick