Couple of quotes from a Big Ten board:
"Redshirt junior Danny Vanden Boom likely would be the next quarterback in line if both Mertz and Wolf are out. After Nebraska, Wisconsin hosts Purdue before visiting No. 13 Michigan. Vanden Boom appeared in three games in 2018, completing the only pass he attempted for a 3-yard touchdown."
"Might not be a game, however. There are 9 positives (for now) and the threshold the B1G put in place is <5%. 9 out of 115 would be higher than 5%, assuming they are all confirmed positive. And if that were the case, Wisconsin would not play a game for 3 weeks."