Helu, 27, has previous experience in English rugby having played for Bristol, while Vea, 24, joins with three years of New Zealand NPC experience under his belt with North Harbour.
Vea won his first four caps for Tonga this year while Helu was first capped for his country in 2011 having also been a part of Tonga’s World Cup campaign later that year. Both players represented Tonga at the recent Pacific Nations Cup.
Vea, whose cousin Steve Mafi plays for Aviva Premiership rivals Leicester Tigers, said: “I’m really looking forward to the challenge of playing in the UK with Wasps. Wasps were one of the first European clubs I started watching as a youngster and I think I will learn a lot about scrummaging in the Northern Hemisphere. It is a big challenge for me but I can't wait to get stuck in."
London Wasps Director of Rugby Dai Young said: “Both of these players will add important depth to the squad. Taione is a developing prop and he joins a group of young front row players here who are all pushing each other very hard. William is a hard running player who covers a few positions in the backline and we’re looking forward to their arrival.”