We have already noted how Public Health England issued a statement in which they claimed that someone could only pass on the coronavirus (covid-19) if they were showing symptoms. This isn’t true and it was known not to be true at the time the statement was issued.
Recently, Chris Whitty, Chief Medical Officer for England has been putting out some projections about the mortality rate for this virus. Based on WHO and other data these projections seem overly optimistic.
Overall, probably around 1% of people who get this virus might end up dying based on the Chinese experience.
But let’s take 1% overall as the current reasonable figure. It goes up a bit in people who are older and more vulnerable. It will be much lower than that in younger people who have no other health problems 
Now let’s compare 1% and “goes up a bit in people who are older” with some other sources:
According to the WHO (6/3//20) the crude mortality rate is between 3% and 4%.  The crude mortality rate is simply the reported number of deaths divided by the reported number of infections. Of course, as the WHO points out, if we take account of the fact that many mild infections go unreported the actual mortality rate is certainly lower. On the other hand; some people who have contracted the virus and who appear in the figures for reported number of infections have not died yet but will die. This will push the figure the other way.
The crude mortality rate in Italy as of today can be calculated: total reported cases = 5883. Deaths: 230. Rate: 3.9%  (A slew of new cases were reported yesterday so the figures will be skewed towards underestimating the mortality rate as a percentage of these new cases will die – and have not yet). This corresponds neatly with the WHO figure.
[Update: as of 17.50 GMT 8/3/20 the revised figures for Italy as published by the Guardian are 366 deaths and 7375 cases. This gives an approximate crude mortality rate of 5%].
As for “it goes up a little bit for those who are older” consider these figures from an official Chinese source.  While the mortality rate for those in the age bands up to 50 (per 10 year step) is always less than 1% the figures change significantly for those over 50. 50-59: 1.3%. 60-69: 3.6%. 70-79: 8%. 80+ 14.8%. 14.8% is not “a little bit”. This sharp increase for those in older age bands is reflected in the Italian experience where the average of deaths is given at around 80 years old. 
Also, it appears, according to a report in the Independent, that in Italy 10% of cases result in an admission to intensive care:
In a letter to the European Society of Intensive Care Medicine, seen by The Independent, critical care experts from the country [Italy] warned: “We are seeing a high percentage of positive cases being admitted to our intensive care units (ICUs), in the range of 10 percent of all positive patients. We wish to convey a strong message: Get ready!” 
Chris Whitty’s figures are probably based on two assumptions. 1) There has been a massive underreporting of mild cases and 2) the better quality of healthcare in the UK compared to China will ensure lower mortality rates. But neither of these assumptions really stands up. While there may well have been underreporting of mild cases in China (there are reports for example of people being turned away from hospitals) this is unlikely to be the case in Italy – with a more sophisticated health infrastructure. And; the same argument applies to the idea that the UK’s superior healthcare will see lower mortality rates. Is Chris Whitty sure that the UK’s health service is really far superior to that which is available in Italy where (see above) the latest crude mortality rate is 5%? Most doctors according to a Guardian survey think the NHS is not able to cope with an epidemic.  Chris Whitty himself acknowledges that there may be a shortage of beds. Already the advice is that mild cases should simply stay at home. It looks like Chris Whitty’s assumptions may be motivated as much by a desire to minimise panic as to provide an accurate assessment.
The point of this post I should hasten to add is not to inculcate panic. I just think it would be better if the authorities were frank about the situation. Of course, as in any such situation the authorities will be acting on a clear list of priorities. Something like:
- protect the economy and profits
- project an image that the authorities are doing vital and necessary work in the public interest (i.e. PR for their own position)
- protect public health
- communicate in a democratic and scientific fashion with the population
(On 2. above the UK Health Secretary has already been caught making up stories about government being able to ensure food supplies to people ‘self-isolating’ at home).
Finally, Chris Whitty may turn out to be right. It is not impossible. But there does seem to be a striking difference between his projections and figures from the WHO and from Italy and China. It would be very interesting to see the basis on which the UK figures have been calculated. But either Chris Whitty did not provide these to the press or they were not reported – at the conference in which he gave these estimates.
As a footnote; look at the response from the NHS to the warning from Italian doctors: (last paragraph). Let’s hope they can manage a virus epidemic as well as they can write PR puffs!