Reed, 25, suffered a shoulder injury in Brisbane’s last game of the NRL season against Canterbury at the weekend and requires an operation.
He had previously returned to action early following a collarbone injury, but has now been ruled out of contention for Steve McNamara’s squad.
McNamara said: “It’s a bad one. The full extent isn’t quite known as yet, but he won’t be available for selection which is disappointing.
“Jack’s really upset, he did it in the last game. He’s a tough player and he’s been desperate to be available, and his collarbone would have been fine in a few weeks, but this new (shoulder) injury is worse than what he thought it was going to be.
“We’ve had confirmation that it needs operating on immediately, so it’s a significant injury.”
Speaking at the unveiling of new World Cup sponsor getthelabel.com at a specially arranged session at a primary school in Warrington, McNamara remained upbeat about his squad.
He added: “I’m still really confident. It’s very disappointing for Jack and us, but that’s why we’ve had programmes for years, so what when stuff like this does happen, we have people to jump in to the squad.
“Leroy (Cudjoe) and (Kallum) Watkins have been in the team for the majority of the last few years – Zak (Hardaker) has failled in – and we’ve got a few other strong candidates as well.
“It’s disappointing (to lose Jack) but it’s not terminal for us as a team.”
Reed played all four games for England at the 2011 Four Nations.
Meanwhile, McNamara is hopeful about the fitness of Melbourne star Gareth Widdop, after he returned to action early from a dislocated hip, which had threatened to end his entire season.