After the convincing defeat to India at Lord's last month, Vaughan was among Cook's critics as he called for the 29-year-old to be replaced, but victories in the past two Test matches have encouraged the former England captain to retract his comments.
"No question, I was wrong," Vaughan admitted on BBC Radio 5 live. "Two-and-a-half weeks ago, I said a break would've done him good.
"But the England and Wales Cricket Board stood by him, he was strong and said, 'I'm the man to carry this young team forward.'"
England head into the fifth Test at The Oval, which begins on Friday, leading India 2-1.