we know that the vikings got as far as newfoundland. You’re the first person I’ve ever heard say that they brought diseases with them that caused die offs.
Do you have references or are you just correlating the dates.
Mere conjecture on my part based on the timeline, but here’s a good discussion on the subject:
http://www.strangehistory.net/2014/03/17/didnt-vikings-bring-disease-americas/