The point of a model like this is not to try to predict the future but to help people understand why we may need to change our behaviors or restrict our movements, and also to give people a sense of the sort of effect these changes can have. […]
None of us know what lies ahead. But the wise uncertainty of epidemiologists is preferable to the confident bluster of television blowhards. The one thing we can be confident of is that enormous risks lie ahead — including a huge loss of life — if we don’t take aggressive action.
The possibility for the UK to reach herd immunity (a marketing slang for natural selection at this point, lacking of clear measures to protect the elderly or to strengthen the health system) is based on a lot of untested assumptions.