I would be interesting in finding a medical doctor's or a biologist's perspective on this. Suppose we consider the NHS to be a body, in the greater environment of the internet/economy/government. What traits of that environment led to the evolution of this ransomware pathogen? Now that we have had a massive, but not lethal exposure to it, how can we build up an immunity? What changes to the environment would eliminate the refuges of this pathogen?
It's like when smallpox was brought to the New World... the NHS's internal IT, existing in isolation, hasn't developed immunity to pathogens which are common elsewhere (i.e. they stopped installing Windows security updates).
There may be certain mission-critical, non-internet-connected machines for which it's still safer not to install updates, but for the average doctor's workstation it will probably become the norm to install Windows patches.
Where I live, doctors have more freedom in how they run their clinics and IT. That probably causes its own problems, but at least they're free to run a modern version of their OS and keep it patched. This kind of virus wouldn't affect us the same way since there's no top-down tech policy which prevents individual doctors from following good security practices; in fact, if you just follow all the recommended settings when installing Windows/macOS, you'll end up with automated patching by default.
So if you really want an epidemiological analogy, maybe the best one is a monoclonal, monoculture crop (e.g. the Gros Michel banana) being decimated by a pathogen which has just evolved the ability to infect it: take down one banana, and you take them all. Take down one English doctor's computer...
