There is an irony in this.
If the original Norse settlement had succeeded and the peoples of the north america had sporadic to regular contact with trade from northern europe, and if they had intermarried on occasion, probably what happened 5 centuries latter wouldn't be possible. That is, they being almost wiped from diseases (the colonizers actually explored a post apocalyptic new world). Not only they would be more resistant to diseases they probably would have had horses centuries latter and some metal weapons and metal production.