How to read the Covid-19 numbers
In the news today: the world passed 1 million cases of Coronavirus.
It’s a great headline, but what does it actually mean?
The number represents the ‘recorded cases.’ A recorded case is someone who tested positive for the virus. So it is someone who was ill, was tested, and tested positive. Anyone who was ill, or was infected but asymptomatic, and was not tested is not included in this number.
The number of people tested and the circumstances in which they are tested varies enourmously. In some countries, people are only tested if they are sick and go to hospital. At that point, if they show symptoms, they are tested. So that number, for example in the UK, represents an equation something like this:
Number of people sick enough to go to hospital + number of available tests = how many people are tested, of which x% have Coronavirus
This number really only tells you how many sick people in hospital, who could be tested, had the virus. This is then extrapolated by most of the media as how many people have Coronavirus, or how many ‘recorded’ cases there are. The latter is more accurate, but still a relatively unuseful number.
Some countries are only testing sick people in hospital. Others are testing randomly across the…
