At this point, I think it's pretty clear that New Zealand's approach couldn't be expected to lead to New Zealand-style results in places that aren't relatively small islands a thousand miles or so by sea from the nearest neighbour. There are just too many infections that slip through the net even after banning most people from travelling there and requiring returnees to quarantine in state-run facilities at their own expense for two weeks - it works for them, but the same level of per-capita leakage in a country with even ten times the population would cause such a stream of imported cases spreading Covid in the community that I don't think it'd ever be able to drop below level three restrictions, let alone beome Covid-free.

In reality the UK probably wouldn't even be able to manage that - for example, we have a constant stream of lorry drivers coming in from locations throughout Europe to destinations throughout the UK, many of them with absolutely vital goods, and that's a great way to spread Covid from country to country. Somewhere like the US would stand even less chance.