Published 7 April 2020
Pending the next few days, peak Covid-19 should be conquered. Unfortunately, like many hills that you climb, you get to the top and realise there is still a long way to go. There are three big challenges ahead:
ongoing demands from COVID-19, which could last for many months
meeting the demand from unmet activity
getting people back to work
"Lives and livelihoods".
No one knows what the exit strategy is for the UK. Partly because no one has any idea if they have had the disease, can catch it again, or unintentionally spread it to the auntie’s neighbour’s grandfather. Lots of good work is being done to understand more to help.
Perhaps the exit strategy sits somewhere between the extremes of the US and China, or a choreography involving the best of both - see minute 21 of this excellent discussion.
What we can say with some certainty is that the disease will not be allowed to continue spreading through the population - even Sweden who opposed a lockdown is now considering one. In a hypothetical scenario where the spread of the disease is "managed" so that the number of sick people does not overwhelm the health service (e.g. no more than 3,000 critical care beds occupied at a given point in time), it could take up to 15 months before enough people have had the disease to enable a form of herd immunity.*
Aside from the ethical and equitable implications of an option like this, 15 months is too long.
The solution is unlikely to be simple, although it will need to be communicable and brought into by a large and quite disparate population from London to Cornwall.
------ * Herd immunity is calculated as 1 / 1- R0. Where R0, the rate the disease spreads, is calculated as a function of: the rate of contacts; the probability of infection; and the duration of infectiousness. Before the lockdown, this was around 2.4, which suggests herd immunity would only be achieved once 60% of the population has had the disease. But R0 is higher in denser places like London and other city centres (we see the impact of this in the data). Herd immunity "achieved" when more like 80% of the population has been infected. This is why Covid-19 is a disease of density.