Vaikona, absent since 9 May with a groin injury, took just four minutes to open his account, crashing over in the right corner after collecting Henry Paul's pass.
The Tongan then sprinted 35 metres to score after a mesmerising run by Paul had carved the Blue Sox defence apart.
His two tries helped the Bulls towards their fifth straight win as they increased their lead over Leeds, who thrashed Huddersfield 84-6 on Friday.
Halifax - watched by a crowd of 9,342, a record home Super League attendance for the club - made life difficult for Bradford but Matthew Elliott's men did more than enough to complete the double over the Blue Sox.
Bradford were still without Robbie Paul, Nathan McAvoy and Michael Withers but their backs - with 17-year-old Leon Pryce again catching the eye - were too hot for Halifax to handle.
Warrington maintained their top-five challenge after they completed a double over the London Broncos at Wilderspool thanks to a hat-trick from Simon Gillies.
The Wolves, who defeated the Broncos 30-18 at The Stoop in April, made a dream start and were 10-0 up after eight minutes before completing a 28-14 victory.
Bright Sodje scored twice as the Sheffield Eagles ran out 24-6 winners at Wakefield to leap-frog their hosts and all but end their relegation fears. Sheffield are now 10th with an 11-point advantage over Hull at the bottom.
Kevin Gray notched 22 points with three tries and five goals as Hull Kingston Rovers, the Northern Ford Premiership leaders, beat the bottom club Doncaster 42-16.
Doncaster battled all the way with John Okul scoring twice and Guy Adams touching down but were no match for the title favourites.
John Wray countered with two of his own and Rob Danby, Chris Kitching and Paul Fletcher also added tries.
Second-placed Leigh maintained the pressure on the leaders with a 24- 18 victory at Featherstone Rovers. Two tries by Rodney Bowker either side of the interval proved decisive as the visitors registered their sixth win in seven matches.
Jamie Rooney's second try seven minutes from time came too late for Featherstone, now seven points behind Leigh in sixth spot.
Richard Pachniuk produced an excellent performance against his former team-mates in third-placed Hunslet's 10-try rout of Oldham.
Pachniuk scored two first-half tries and set up two more for as he took control of a one-sided match which the Yorkshiremen won 56-12. When Pachniuk went in for his first try he recorded the 100th touchdown of his career.
A second-half drop goal by Greg Pearce proved to be a match-winner for fourth-placed Dewsbury, level on points with Hunslet, as they beat Swinton 27-26.Reuse content