O'Shea said: "It's a pretty happy camp at the moment, especially with the defensive situation with the clean sheets.
"I hope they will stay clear of injury because they have been a major influence on keeping the clean sheets."
Vidic had to be substituted because of concussion during Saturday's 4-0 win over Wigan. But that was mainly as a precaution, and there are suggestions that the Serbian defender is in line to be given a new contract.
United do not normally hand out new deals until 12 months before a player's contract expires - but such has been Vidic's impact they may make a special case for him.
As O'Shea made clear, Vidic also gives opponents a headache at the other end of the pitch.
"Nemanja is big goal threat as well," he said.
"You know if the ball is going towards him when he makes a run there's a good chance of it being a goal. Other teams are picking up on that now, and he's becoming really tightly marked."