Scrum-half Moates suffered a knee ligament tear in last weekend's Amlin Challenge Cup clash against Grenoble and will be sidelined for six to nine months.
Centre Jacobs tore ankle ligaments in the same game, and will be out for at least six months.
Both Wasps stars will need surgery.
"It's a huge shame to lose two players for the remainder of the season in one go and it's a real blow to Jack and Ben," director of rugby Young told Wasps' official club website.
"I know they will be working incredibly hard with our medical team to get back right."