What does a case of Covid-19 really mean?

‘What’s in a name? That which we call a rose by any other name would smell as sweet,’ wrote the Bard. He was referring to a rose which is a rose, instantly recognised by its fragrance and its appearance. But a case of Covid-19 does not fit the metaphor, because it differs wherever you look.

In the course of our evidence gathering activities, we have gone through a few thousand papers reporting studies on all aspects of Covid-19 spread. We found that not very many defined a case of Covid, which is a sign of sloppiness when that is what you are looking for. Those that did, reported different definitions and ways of ascertaining what they meant by a ‘case’.

Now this may seem a pedantic academic remark, but in reality, it underlines the chaos which has crept into Covid-19 science and decision-making. After watching the briefing by the Chief Medical Officer Chris Whitty on 9th September, where he described his worry about the increase in cases and compared the situation in the UK to other countries, we asked the question: what does a Covid 19 case mean and how do different nations define a case? We looked at the definition of a case given by the World Health Organisation, the US and EU Centres for Disease Control, China, Italy, Spain, France.