Vansant represented United States national team on an international competition for the first time at the 2015 Pan American Cup. She led the team to gold medal with a tournament-leading 50.4% kill percentage to go with 81 total points, and earned "most valuable player" and "best outside hitter" honors for the tournament. At the 2015 Pan American Games, she was the top scorer for the Team USA in five of their six matches and selected as the "best outside hitter", while the Americans winning the title. She also helped Team USA to capture the gold medal at the 2015 NORCECA Championship and was on the preliminary round squad at the 2015 and 2016 FIVB World Grand Prix, where Team USA won the gold and silver medal, respectively.