It can't be stressed enough that these people are not talking about actual herd immunity, in which a virus is driven out of the population. That is not achievable without a vaccine. Deadly viruses don't miraculously disappear completely because they made enough people immune.
If that happened we wouldn't need vaccines. Polio, measles, smallpox and so on would just have vanished of their own accord! It isn't herd immunity they're pursuing, it's endemic disease. That's the stage after an epidemic when deaths settle down to a constant lower frequency.
The false use of the term herd immunity, which refers to the disappearance of the virus, is leading people to imagine that this mythical goal will be the end and it will all go away. It won't. Deaths may be hundreds a week rather than hundreds a day but they won't stop.
While other countries are pursuing rigorous suppression and possible eradication to save lives, the UK just wants to get through this to a time when people stop caring that sickness and death are constantly present in the population. That's what endemic means and that's the goal.
When an endemic state is reached the epidemic has ended, yes. It hasn't been defeated, that's just what epidemics do, left to their own devices. But the disease hasn't gone. Nobody who has protected themselves will be able to go out in public, because virus will still be there.
Do people realise this? Does Johnson realise this? I suspect not, thanks to the misappropriation of the unrealistically optimistic term "herd immunity" from vaccine science. But if this is the goal, be prepared to isolate yourself until the vaccine is available.
