The problem with ignoring this is that the reason for the lack of vacuum could be a sheared vac pump drive shaft, which if it affects the accessory drive on the back of the engine, is going to cause an instant and total engine failure.
Very unlikely, and the vac pump shaft has a plastic section which is meant to shred if the vac pump jams, but I would not play with this.
Much more likely a hose has come off, but you need to be sure (which should take all of a few minutes).