Schumacher, himself a seven-time world champion, remains in a medically-induced coma following the accident whilst skiing off-piste in the French Alps.
"I was as shocked as everybody else in the paddock," Vettel said in a press conference on the first day of testing ahead of the 2014 season in Jerez, southern Spain.
"I have known him for a long time and looked up to him my whole life.
"I got to know him better when he made his comeback and we spoke to each other regularly.
"We still don't know what shape he will be in when he wakes up, which is awful for his family and friends.
"I am still in shock, but hoping the miracle happens and he can be the same guy he was before."
One of Schumacher's former teams Mercedes has included the message "keepfightingmichael" on their W05 car for the new season, which has become a hastag on the social networking site Twitter for fans to send their own tributes to the 45-year-old.
Vettel added that he hadn't been to visit Schumacher in the Grenoble hospital where he is being treated.
And he echoed the sentiments of Schumacher's wife, Corinna, who asked for the press to respect the family's privacy.
"I'm sure the pressure from the media on the hospital didn't help.
"It is about Michael and his family and it is good for the hospital to be able to focus on their job."