I read this novella (or perhaps a very long novelette) about 20 years ago in a collection that was probably somewhat older.
During the Blitz, the volunteers who dug the rubble caused by the bombs to find survivors slept very little. So their judgments became impaired. For instance, one became convinced that Hitler was bombing London just to kill him personally.
The POV character in this story has a comrade-in-excavation who keeps finding survivors in a preternatural way. Little by little the former becomes convinced that the latter is a vampire, who follows the smell of the living people under the rubble.
But he is recruited in the army, and leaves London to fight abroad. He is hurt and sent in hospital in the UK. There another of his comrade-in-excavation (or maybe a son of one) visits him and tells him, among other news, that the "finder" has died digging survivors during an air raid.
IIRC, a blast had projected a piece of wood straight through his chest. Since this is the traditional only way to kill a vampire, the doubt of whether he actually was a vampire remains.
On the other hand, since the "finder" had come later than all the others to London, his hearing had not had time to be impaired by all the explosions the others have been submitted to. So he might have been able to hear sounds the others did not hear. In that case the story might have been completely "mundane". But it was clearly written in such a way that the reader thinks like the exhausted POV character and is convinced the other one is a vampire. And it was in a SF&F collection !
