England's Borthwick keen for swift end to red card fall-outs
As happened to Farrell last weekend, Vunipola saw his initial yellow card upgraded to a red by the recently introduced bunker review system.
Vunipola was dismissed for a head-high challenge on Andrew Porter early in the second half at Lansdowne Road.
That offence threatens Vunipola's involvement at a World Cup where he is the only specialist No. 8 in England's squad for a tournament they start against Argentina in Marseille on September 9th.
England kicked off without Farrell, the son of Ireland coach Andy Farrell, after Borthwick left the fly-half out of his matchday 23.
Farrell faces an independent disciplinary panel on Tuesday after World Rugby appealed against the controversial decision to downgrade his red card for a high shoulder-led challenge on Taine Basham during a 19-17 warm-up win over Wales at Twickenham to yellow.
Borthwick, refusing to be drawn on Vunipola's dismissal, said: "I'm not going to comment upon the incident specifically because it goes into a disciplinary process this coming week.
"Probably as every England fan, I feel disappointment in the game today and I said beforehand we want 15 players on the pitch for 80 minutes of every game.
"You're playing the number one ranked side in the world in their stadium and to go to 14 men it becomes a very difficult task at that point in time."
The former England captain added: "Hopefully we will find a conclusion on both matters this week and it won't go into another week. Once I have all the facts, I will deal with them."
England were already well behind before Vunipola's 53rd-minute sin-binning was upgraded.
Ireland scored five tries, all through their backs, with Bundee Aki, Garry Ringrose, James Lowe, Mack Hansen and Keith Earls -- winning his 100th cap off the bench -- all crossing England's line.
England managed a late try through replacement prop Kyle Sinckler.
But a fourth successive Test without a try by one of their backs spoke volumes about England's attack.
'Good, bad and ugly'
"Whilst I'm incredibly disappointed with the result, the players kept fighting," said Borthwick.
He added: "When it was 15 against 15 it was a tight battle, unfortunately it didn't stay 15 on 15."
Ireland coach Andy Farrell was not entirely happy with his team's performance.
"It had a bit of everything: good, bad and ugly," he said.
"I wasn't too happy at half-time. We had them in a place where we could push a little bit harder and make it a little bit easier for ourselves but we didn't kick on.
"I was really pleased that we found or rhythm back into the game. I thought we scored some great tries.
"Obviously the story of the day is it's very fitting that Keith gets his 100th cap and we made sure he does that with a win and also him scoring a try in Keith Earls style in the corner just made the day for everyone really."
