I think that is a slippery slope. Once it was known, other countries did nothing to stop the spread either by allowing free travel rather than going into a lock

I think that is a slippery slope. Once it was known, other countries did nothing to stop the spread either by allowing free travel rather than going into a lock-down mode. Each country put their economy ahead of the well-being of their citizens. The US is still allowing free travel between states knowing full well that its going to make it worse.