More Viral Arithmetic

'Everyone has a plan until they get punched in the face' 
(Attr. to Mike Tyson.)


After the UK Prime Minister's press conference two days ago (12th March) on Covid19, people have started to understand the scale of the epidemic foreseen by the British government; for example the Independent published an article yesterday crunching the arithmetic: to get herd immunity requires at least 60% of the population to become infected with the virus; in the UK that is 39 million people, so if the CFR is 1% this would give 398,000 fatalities. (Note - as I recall, only last week the government warned the Scottish government to expect 100,000 fatalities in the worst case).

It has to be admitted that the UK government's naming of the 4 stages of its Covid19 plan - containment, delay, mitigation and research - was confusing, as it is clear that since the third week of February (at the latest) the government's aim has been not to contain the virus in the UK but to delay the epidemic - well before it officially moved from the 'containment' to the 'delay' stage on 12th March.  It is, therefore, not surprising that many are unhappy and shocked.

However, all the comment which I have seen has been about the total number of infections, but the rate of infection the government seems to foresee is hardly less eye watering.

If  we assume a total of 40 million infections in the 1st wave of the epidemic (fractionally over 60% of the UK population), and that 50% of the infections occur in a three week peak, that gives an average of nearly 1 million infections a day during the peak three weeks.  It is expected that about 5%  of those infected become critically ill - 50,000 a day for three weeks in a country with 4,000 ICU beds, of which 80% are currently in use.  How is that not going to overwhelm the NHS?  And we know from Italy and Hubei that if a health service is overwhelmed the case fatality rate rises.  But even at 1% CFR you could expect maybe 10,000 per day in the worst period.

However, long before that, if China appears to have suppressed the epidemic with say 5,000 casualties overall, I cannot see the UK government sticking to its current plan, no matter how resolved to do so it is now.