The former Reading striker has been called up to the final 23-man panel to face Greece at the Aviva Stadium on November 14 after proving his fitness
The Baggies striker was not named in the provisional 26-man squad which was named last week, with Trapattoni indicating that he was suffering from an injury complaint.
However, after playing 70 minutes last night against Southampton, Long has been deemed fit enough by the Italian coach to take part in the fixture on November 14.
Norwich City midfielder Wes Hoolahan retains his place in the squad, but Milwall striker Andy Keogh and Crystal Palace defender Damien Delaney have been placed on standby for the game, as have uncapped duo Shane Duffy and Conor Clifford.
The squad will join up in Dublin for training on Sunday, November 11.
Ireland squad to face Greece on November 14
Westwood, Forde, Randolph, Coleman, O’Shea, O’Dea, Kelly, McShane, Ward, Clark, Andrews, McCarthy, Fahey, Meyler, Whelan, McGeady, McClean, Brady, Hoolahan, Doyle, Cox, Walters, Long
Keogh, Duffy, Clifford, Delaney