Coronavirus – has the Emperor got any clothes?

It seems to be universally agreed, by journalists, politicians, scientists and everyone else, that China, and potentially the rest of the world, is in the grip of a devastating infectious disease epidemic. I have seen no comments questioning this. But there are questions that should be asked.

1. Is this a new disease? Although this virus is a new one, at least as a cause of human disease, coronaviruses as a group are very common, causing perhaps 10% of common colds, and most people have been infected with one or more of them at some time. But as this is a previously unidentified form of coronavirus, we are justified in regarding it as a new disease.

2. How infectious is it? One estimate that I have seen put its ‘reproductive number’ at 3. That is, each case would infect three other people. While that is plenty for the establishment of an epidemic, it is well short of that seen in a number of other infectious diseases – for example the corresponding number for measles is estimated at 15-20. (That is admittedly an extreme example; estimates for most common infectious diseases lie in the range 2-7).

So it is infectious, but not wildly so – which calls into question the need for the extreme measures being adopted.

Face masks are one form of protection widely used Are they needed? Are they any use? Answering this question needs an understanding of how such infections spread. An infected person will liberate droplets carrying the virus – not just when coughing or sneezing, but when talking or even just breathing normally. Most of those droplets can be trapped by a face mask, as they are relatively large. But they are mainly water, which will evaporate rapidly in the air, leaving tiny particles (known as ‘droplet nuclei’). These carry the virus, and it is this form that is breathed in by others who thus become infected. But these droplet nuclei are too small to be trapped by a simple face mask. So a face mask will cut down the extent to which an infected person will pass on the disease, but offer virtually no protection against becoming infected. (There are also other limitations to a simple face mask, but one will do.)

3. How dangerous is it? While there have been a large number of deaths in China, that needs to be related to the number of cases. That is done by dividing the number of deaths by the number of cases (giving the ‘mortality rate’). The reports from China indicate a mortality rate of between 2 and 3%. That needs to be qualified. While we can be reasonably confident of the number of deaths, we are much less sure of the real number of cases. When a new disease occurs, and/or when there is pressure on resources, it is inevitable that the necessary tests are more likely to be done on subjects with serious disease. Those with a milder disease – and even more so those with no recognisable symptoms – are less likely to be investigated. If we include these subclinical cases, the number infected will be higher, and hence the actual mortality rate will be lower than this estimate. It is repeatedly seen, when a new disease emerges, that initial estimates of mortality are very high, but then drop substantially as more of the less severe cases come to light.

Even if we accept a level of 3%, this does not make it the ‘deadly virus’ that has been reported. This is similar to the mortality rate of a typical outbreak of influenza.

4. Are the resources being devoted to this disease justified?  The world is still suffering from many other infectious diseases, with many more deaths than those caused by this coronavirus. These diseases could be controlled or even eliminated if sufficient resources were available – cholera, malaria, tuberculosis for starters. If a fraction of the resources being poured into controlling this epidemic were applied to, for example, providing clean water and proper sanitation across the planet, we would eliminate cholera (and other water-borne diseases).

5. Why are these questions not being asked?  That brings me back to the title of this blog.

The Emperor’s New Clothes  is a short tale written by Hans Christian Andersen, about two weavers who promise an emperor a new suit of clothes that they say is invisible to those who are unfit for their positions, stupid, or incompetent – while in reality, they make no clothes at all, making everyone believe the clothes are invisible to them. When the emperor parades before his subjects in his new “clothes”, no one dares to say that they do not see any suit of clothes on him for fear that they will be seen as stupid. Finally a child cries out, ‘But he isn’t wearing anything at all!’” (Wikipedia).

No further comment necessary!

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