Cook faced criticism for his leadership throughout the disappointing tour of Australia in the winter, and Vaughan believes that the spotlight is on the 29-year-old again as he prepares to lead the ODI and Test squad into series against Sri Lanka and India.
"Alastair will be excited but also very nervous," the former England captain told BBC Sport. "The pressure is on him. Any failure, any disappointment will be jumped on by a lot of people.
"Even though he's won an Ashes and won in India, Cook will probably feel like this is a fresh start, what he's going to be judged on as an England captain.
"The combination of Cook and Peter Moores is going to be under scrutiny. We are all looking to see how they are going to come out and play."
The first ODI against Sri Lanka takes place at The Oval on Thursday.