We needed the borders shut completely before Christmas. That was never ever a possibility.
It had moved out beyond Wuhan last year. Why do you keep pushing an idea that’s clearly wrong?
But you are wrong Gandalf - 100% wrong on this topic.
It is about numbers. If a relatively small number of people are coming in, you can monitor and quarantine them. If masses of people are travelling in and out, that renders it impossible.
Once you have an outbreak, you can go mad on controlling it as they did in South Korea - but having done that, you need the stringent border controls to keep it contained.
Until there is a level of herd immunity or a proper vaccine is available, you have to decide whether you want to control the spread and border controls are a major part of that (for big countries like China or the USA, you might also need internal border controls too).