I like the way you paint and contrast the two scenarios. Good work!
I understand the 600,000 fatality case, but less so with the other.
Since we all happily have similar population for ease of comparison, knowing hospitals in Hubei were and now Italy are on their knees with X0,000 infected over a period of a couple of months, what do you think is the likelihood that our precious nhs might "cope", achieving 1% fatality, with 40,000,000 infected even if spread over twice/thrice/N times as long, when we are talking about some 1000 times more infected?
You've hit the nail right on the head. The implicit assumption in my "better" case scenario is that the infection rate is slow enough that the NHS can cope.
At the current growth rate of infections, there is little prospect of the NHS coping. We've got to get that down -way down - in order to stand a chance. Again, we can put numbers to this. Let's assume the optimum scenario where 90% of those infected have such mild illnesses they don't even realise themselves. Of the remainder, 5% will need ventilator support (Chinese data, this fraction approaches 10% in Italy but we'll look at he best case). The NHS has 7000 respirators. Assuming that 5000 of those ventilators are available and a patient needs on average 2 weeks on one (data from China was that of htose who died, many were on ventilator support for 10-14 days). That means the NHS would have a capacity to cope with 2500 new severe cases per week. That in turn means 50,000 new cases per week. Herd immunity requires 4 million overt infections. At this rate, it'll take 18 months to reach the level of resistance required for herd immunity without the NHS collapsing under the strain. By my quick back-of -the-envelope calculations, we'd need about 50,000 ventilator places to cope, given the rapid increase in cases. That's just not feasible. I don't think the herd immunity idea will work.
I feel that the only chance is to require that pubs, clubs, cinemas and other public gatherings to be halted immediately. It looks like the government's also come to that conclusion, with Johnson's advice that we should now all avoid bars, cinemas and theaters etc. It's a start, but doesn't go far enough. Expect more stringent actions to follow in short order! I suspect that we'll see most pubs and clubs being closed by Monday and further restrictions before the end of next week. The one bright spot is that people are beginning to vote with their feet, and avoiding those places unbidden. That is probably the most helpful action any of us can do at present - drastically cut down all social interactions.
@DCLane I take your point that mortality will be lower with at risk groups self isolating. That's true, but few will be able to completely shut themselves off from society for 3 months or more, so the benefit will likely be less than what we hope.
This BBC article goes into this in more detail - the numbers are different (not surprising given my naively simplistic models) but the message is similar.