We'd have to live in literal solitary confinement for months, the borders would have to be closed permanently, and the amount of collateral damage to health and economy would be off the scale. And to maintain the situation, miserable, life wrecking restrictions would need to be in place forever. It's completely impractical. The only reason Australia and New Zealand have fared quite well is that they're sparsely populated and have relatively low levels of international traffic. Their situation isn't sustainable since they're going to have to open their borders at some point.