Why do you say "air travel" and not "international travel"? Before COVID got here, domestic air travel was perfectly safe, and a boat from China is just as capable of carrying COVID as a plane from China is.
I agree especially in dense places like Europe (thinking of Italy outbreak) early border shutdown for non essential travelling would have helped in addition down the line. I’m not sure boat travel is comparable to air travel in both mass and interconnection around the globe. It would probably have also been warranted but main driver here was globalization / air travel.
