But the Welsh region's head physio Chris Towers said that the winger should be in contention to play again this weekend.
"We've been monitoring Tommy very closely over the last month, as well as being in close consultation with the Ireland management regarding his progress," he said.
"He has made considerable progress over the last couple of weeks, up to the point where we've been able to get him up to high level functional sessions without any adverse reactions.
"As such, we're looking to reintroduce Tommy to team training this week with a view to making him available for selection on Saturday.
"If everything is positive, he will then be able to return to Ireland camp and be involved in their remaining Six Nations fixtures."
Declan Kidney's men resume their Championship campaign against Scotland at Murrayfield on Sunday, February 27, before facing Wales in Cardiff (Saturday, March 12) and England at the Aviva Stadium (Saturday, March 19).