Cook's leadership skills have been questioned once again following the series loss to Sri Lanka, while the 29-year-old has not scored a century in his past 24 innings in the longest format, and Vaughan believes that the five matches against India will be crucial for the skipper.
"The key is winning," Vaughan, who captained England in 51 Tests, told BBC Radio 5 live. "That's what will define Alastair Cook over the next five Test matches. Can he beat India at home?
"I don't feel it's the right time to change the England captain. Alastair Cook's the man. He's certainly the one who can change the way England are playing."
The first Test begins on Wednesday morning at Trent Bridge.