Which remains true. The only thing that would work is forced quarantine for all travelers for the hole incubation time so you could be absolutely certain they'r

Which remains true. The only thing that would work is forced quarantine for all travelers for the hole incubation time so you could be absolutely certain they're not carrying that virus before letting them back into society. That wasn't going to happen, and anything else doesn't stop the virus from entering in some way. And even this could potentially be unsafe as the virus could potentially mutate. Honestly, anything but herd immunity with vaccine isn't going to cut it with an easily spread virus such as this. (Still not a guarantee, just highly likely to work)