The Serbian central defender and club skipper was a surprise absentee from the 19-man squad which jetted off to Thailand on Wednesday night to start their summer tour of Asia and Australia.
United initially failed to specify why Vidic was not on the plane, but a spokesperson has now confirmed that the problem is not serious and he should feature for David Moyes' side at some point on the tour, with games lined up in Australia, Japan and Hong Kong before a match in Sweden on August 6.
"It's nothing serious," they told ManUtd.com. "Nemanja has a touch of sciatica [pain stemming from nerves in the back] and may still join the tour at a later date.
"In the meantime, he'll continue his pre-season preparations in Manchester at the Aon Training Complex."