McCarthy found himself at the centre of a tug-of-love between the Republic and Scotland, but insisted it was always Ireland for whom he wanted to play and that is a decision he has never regretted.
He said: "As a young boy when I got the first call-up, I have always wanted to play for Ireland since then and I am delighted to be part of the squad.
"Anything that has been said in the press maybe doubting me here or there, it's just one of those things. Maybe someone has picked something up wrongly.
"I am delighted to represent Ireland and I am delighted to be here this week hopefully trying to get two wins.
"To be honest, these things happen now and again, just people blowing things out of proportion and as a player, you just need to get your head down and keep working hard.
"At that moment in time, I was injured. My physio contacted the Irish medical staff and I think something was said and maybe someone has just blown it out of proportion, as I said."