Wallaby extends Bath stay
Vuna, who has been capped by Australia and Tonga at international level, has made six appearances since joining in January.
The 30-year-old said: "I’m grateful to Todd for giving me the opportunity at the start of the year – I’ve really enjoyed my time here so far, and I’m looking forward to getting a full season under my belt.
"There’s a real hunger and desire to be successful here, and have no doubt that with the players and support staff we’ve got behind us, we can do just that,"
Director of Rugby, Todd Blackadder, commented: "Cooper is a great influence around the place – the way he conducts himself on and off the field is second to none.
"Cooper has worked really hard on his game since he’s been here, and we’re now reaping the rewards. He’s got a real eye for the try line and given half a chance, you know that he’s going to take it,"