Flood made his comeback from knee ligament damage for the Tigers last Saturday and he spent the last two days training with the national team.
But interim coach England coach Stuart Lancaster has decided fly-half Flood needs another game under his belt before making his Test return and released him to play for Leicester against Exeter.
Charlie Hodgson was limited to non-contact work in training today as he recovers from a blow to the shoulder but he is set to retain his place at fly-half for the game at the Stadio Olimpico.
Dickson was initially expected to be sidelined for four weeks after fracturing a bone in his hand during his Test debut off the bench in England's 13-6 win against Scotland.
But the Northampton scrum-half, described as "Lazarus" by coach Andy Farrell, trained with the squad today and is one of three scrum-halves retained in the 24-man squad that will fly to Rome.
Joe Simpson has joined Ben Youngs and Dickson in the trimmed-down squad, replacing Gloucester wing Charlie Sharples as the only change to the squad that travelled to Edinburgh last weekend.
Lancaster will finalise his 22-man match-day squad to face Italy on Thursday morning, before the squad travel to Rome.
Sharples, who missed out on the final 22 last week, joins Flood as one of eight players released for Aviva Premiership action this weekend, along with Dave Attwood, Matt Banahan, Calum Clark, Karl Dickson, Lee Mears and Thomas Waldrom.