Speaking on his RTÉ radio 1 show this morning, host Ryan Tubridy also revealed he will be joined by former President of Ireland Mary McAleese and world champion boxer Kellie Harrington.
Sam Bennett will also appear to discuss his green jersey win at the Tour de France while Jedward will also talk to Tubridy about their attempts to spread positivity using their social media platform.
Niamh Fitzpatrick, sister of R116 helicopter pilot, Captain Dara Fitzpatrick, will also be on the show to speak about the tragic death of her beloved sister in the 2017 Coast Guard tragedy, and the legacy that Dara has left behind.
Tubridy said he was very excited to speak with Dr Fauci, a man with "the most difficult job" who he said is "undermined" by US President Donald Trump "at every turn".
Dr Fauci is the leading public health expert in the United States and he has clashed with Trump on a number of occasions.
Tubridy said: "He has as pretty much taken him [Dr Fauci] off the TV so that he doesn't outshine him, because, actually, Fauci is trusted and liked. And that's why, in some ways, Fauci is available to talk to us tomorrow night, because Trump doesn't want him anywhere near American TV. So, I'll talk to him."
"I think he'll be intriguing," Tubridy added. "Imagine trying to protect the health of an enormous nation like that while being undermined by your own president. I mean, it is impossible. But Fauci, Dr Fauci, has handled himself with such dignity and skill and professionalism and courtesy; it is extraordinary how he keeps going. It is amazing. I look forward to his company no end."
Tubridy also said he was looking forward to talking to Ms McAleese.
He said: "Another great person of enormous dignity joining us tomorrow is former President of Ireland Mary McAleese, which will be intriguing. She has written the book which brings us behind the curtain to a lot of what she has done as president, and as a mother and as a politician in some ways, but also, as a lawyer. Just a very important figure in our country's present and past. "