Vardy has scored in his last nine Premier League games, stretching back to the end of August, and would equal the record set by Manchester United's Ruud van Nistelrooy if he netted for a 10th match in succession at St James' Park.
He has been suffering from a hip injury that caused him to miss England's friendlies against Spain and France and Leicester's manager Claudio Ranieri said he would only play if 100 percent fit.
"Absolutely we hope he doesn’t make it, we’ll be honest about that, but we’ll have to deal with him if does," McClaren told a news conference on Friday.
The Newcastle manager warned, however, that Vardy is not the only danger among the squad who have taken Leicester to third place in the table with only one league defeat all season.
"They have very good players, like Vardy, (Riyad) Mahrez and (Danny) Drinkwater," he said.
"That is why they are one point off the top."
Newcastle, who were bottom after eight games, have recovered with two wins in the last four matches to climb out of the relegation places but attendances have dropped from last season's average of 50,359.
"It’s about showing fight, great attitude on the field and ultimately winning games. If we do that, then crowds will come back," McClaren added.
Newcastle have confirmed that French winger Gabriel Obertan will be missing for another three or four months after having surgery on a hamstring injury.
(Reporting by Steve Tongue; editing by Toby Davis)
