From the latest edition of Current Archaeology (No. 217):
Why did some people survive the Black Death, and others succumb? At the time of the plague – which ravaged Europe from 1347 to 1351, carrying off 50 million people, perhaps half the population – various prophylactics were tried, from the killing of birds, cats and rats to the wearing of leather breeches (protecting the legs from flea bites) and the burning of aromatic spices and herbs.
Now it seems that the best way of avoiding death from the disease was to be fit and healthy. Sharon DeWitte and James Wood of the University of Albany, New York, have examined 490 skeletons from the East Smithfield plague pit in London and found that the Black Death was selective in picking off the already frail. Lesions (damaged bone) associated with earlier episodes of infection, under-nutrition or other forms of physiological stress were present in most of those buried at East Smithfield, where the dead were stacked five deep in the mass graves on a site hurriedly opened on land donated by the Bishop of London.
“This actually contradicts what many have assumed about the epidemic,” says Dr De Witte. “The pattern we observed is of the Black Death targeting the weak, though it did also kill some people who were otherwise healthy. This is consistent with an emerging disease striking a population with no immunity.”