As I see it, the argument against travel based on spreading it (either "importing" or "exporting") is that if we all had the attitude that our one little trip is not going to make a difference in the statistics, then it becomes a self-fulfilling prophecy--we're not going to make a difference. Sure, the likelihood of spreading it is lower with mask-wearing and now with testing at one or both ends of a trip. And if my logic is correct here, travel between two places where Covid is already widespread would take many more trips to budge the statistics than travel to a place that has escaped infection. However, as I understand it, epidemiology is all about statistics. We CAN affect the statistics if every one of us acts as though our actions make a difference. By not traveling even to places where Covid is widespread, I am doing my little bit. It's like recycling, not wasting tap water, and other such endeavors where the contribution of any given individual makes almost zero difference, but collectively it can make a difference.