|Six Nations 2015: Ireland v England|
|Venue: Aviva Stadium, Dublin Date: Sunday, 1 March Kick-off: 15:00 GMT Coverage: Live on BBC TV, HD, Red Button, Radio 5 live, Radio Ulster FM, the BBC Sport website, mobile, the BBC Sport app and Connected TV.|
England full-back Mike Brown has been ruled out of Sunday's Six Nations match in Ireland after suffering a setback in his recovery from concussion.
Brown woke up on Wednesday with a headache after training on Tuesday.
"This morning Mike woke up not feeling 100%," assistant coach Andy Farrell said.
"The right and proper thing to do was to make the call. His health is the main priority here and we need to get him right for the next game.
"The symptoms aren't too severe whatsoever, just a little headache. He's fine in himself and is chirpy enough, but it just isn't worth the risk because his health comes first."
England head coach Stuart Lancaster said the squad's medical staff would continue to work with Brown to "get him back to full health".
England and Ireland, who will meet in Dublin, are the only sides left in the championship with 100% records after two rounds of fixtures.
Lancaster's side beat Wales 21-16 in Cardiff before defeating Italy at Twickenham.
Ireland beat the Italians 26-3 in Rome on the opening weekend, then defeated visitors France 18-11 last time out.