@scalt ,
‘Yes, I know, there's an argument that "a short, early lockdown" would have prevented the following extremely long lockdowns; and this may be true. But I do think that a principal reason lockdown dragged on for so long was because the government frightened the public so much, that they couldn't stomach the idea of normality returning. I think the government would have liked to reopen schools in June 2020, but people were much too frightened for this to be politically possible.’
Lockdowns are a matter of mathematics. You know how infectious the disease is (or estimate it), you have an idea of how many hospitalisations you get per number of cases and, of those, you know how many need ICU. And you know how many doctors, nurses, hospital beds and ICU units that you have. So, you have to stop infections rising beyond a certain level.
And you have measure you can take, between closing retail and schools, suggesting limiting contact numbers (rule of 6 etc) and full lockdown. And, of course, there are trade offs. The harsher the lockdown, the shorter you need to do it for.
And the more limited the freedoms when you ‘unlock’ the longer you can keep going until you have to lock down again.
They got the delta strain (if I remember correctly) wrong at first as they assumed a far higher hospitalisation rate than what occurred. You will always have to err on the side of caution, though.
Lockdowns are the only effective response to a novel pathogen. They aren’t optional.