After a tough road loss, the Browns traveled northwest to take on the Vikings.  The Vikes would score first as AP ran for a 2-yard TD for a 7-0 lead.  The Browns managed to tie it as 2nd-string QB Brian Hoyer found Josh Gordon on a 47-yard TD pass for a 7-7 game.  The Browns took the lead in the 2nd quarter as Hoyer found Jordan Cameron for a 19-yard TD pass and a 14-7 lead.  The Vikes tied the game as Christian Ponder ran for a 6-yard TD to make the score 14-14.  The Browns moved back into the lead as Billy Cundiff kicked a 38-yard field goal for a 17-14 lead and increased it with a trick play as Spencer Lanning found Cameron on an 11-yard TD pass for increasing the score to 24-14.  Blair Walsh managed to get the Vikes within 7 after he kicked a 43-yard field goal for a 24-17 halftime lead.After the break, Ponder ran for another TD from 8 yards out tying the game 24-24. They retook the lead in the 4th quarter as Walsh nailed a 30-yard field goal for a 27-24 lead.  Hoyer found Cameron with less than a minute left in the game for a final score of 31-27. With the win, not only did the Browns improve to 1-2, but they also snapped a 7-game losing streak against NFC teams.
Question: How many points were the Vikings trailing by at halftime?
Answer: 7