As usual Sam you only have a tiny part of the picture. In a world of ubiquitous airline travel there will always be the odd person slipping through any country. In the US, once discovered, then CDC And the airlines hunt down every person who could have been in contact and any suspects rushed off for vaccination and/or isolation. No, we are no any more sophisticated that a great many other countries the planet somehow finds the money to cope. These ideas have been around for decades. In the field of epidemiology it is generally agreed Israel is No 1, Scandanavia 2, Japan 3 and then we are in the middle of the pack from then on out.
The first line of defense has and always will be secure borders - get it Sam - secure borders. As every border is porous to some extent any break of protocol with the odd compromised subject getting through is managed as above. Thx to the village clowns you still support
we have a major fracture in the system here. Out of control borders, busing and flying them everywhere with no controls, no vaccine and no antibiotics and that last one is just dawning on the medical profession. What does it take for the light bulb to go on here. It will take a few weeks for us to really understand what we have done but by then it will be too late.