In Chapter Fifteen Van Helsing brings Dr. Seward into the crypt where Lucy has been buried. There's mention of premature burial, a wide belief in the time of the story. Great measures were taken to ensure that if a person was buried, and they actually were not dead due to lack of embalming, that emergency measures could be taken. Fancy gadgets involving bells with a string leading through the earth and into the coffin—so the alive person could ring in panic—were fashioned. Breathing tubes were also used...just in case. I can't imagine anyone, if they had been buried alive, surviving the terror to actually ring the bell, but who knows? And even if they could ring, who would be in the graveyard to hear?
Also, this segues nicely to the bit about the chewing dead, those who were still alive, or revenants who chewed through their burial shrouds in an attempt to escape their earthly bonds. Recently the skull excavated in Italy, found with a brick in its mouth to keep it from chewing through its shroud, was rumored to be a vampire. Not so, but instead an ancient burial method when people believed that the dead could indeed rise from the grave.