Toby Faletau was one of three Welsh Grand Slam winners - Dan Lydiate and Luke Charteris the others - to start for Newport and set up a nervy final moments after touching down in the 73rd minute.
It wasn't enough to spark the Dragons into life however as Connacht fly-half Miah Nikora exchanged five penalties to Lewis Robling's four to inflict just a second defeat in six onto the Welsh outfit.
And, having battled to no avail against Munster last weekend, coach Elwood was quick to highlight the importance of Vainikolo's two tries to the club as much as the winger.
"A lot was said of how we played last week against Munster. It was great rugby, the best team, full house, derby match, live on TV," said Elwood.
"But ultimately we lost the game and the lads were hurting afterwards and the key for us was to bounce back and the way we bounced back I thought was terrific.
"The way we played the game in the first 60 minutes was fantastic which included two brilliant scores by Fetu'u. It was great to see him on the scoring sheet again.
"It was great for his confidence but also for the team. When your wingers are scoring tries like that it is fantastic. The lads definitely deserved to win the game and I am delighted for them.
"Again it was another huge effort and to win away from home against a quality outfit who have won their last four or five, we are absolutely chuffed."
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