The northern short-tailed shrew produces toxic saliva in enlarged submandibular glands. It has no injecting fangs; the saliva enters wounds as the shrew chews. The effect on invertebrates and small vertebrates is paralysis, and a shrew can subdue prey heavier than itself, including mice.
That capability supports caching. Immobilised invertebrates, particularly beetle larvae and snails, are stored in burrow chambers where they remain alive and edible for some time. For an animal with a very high metabolic rate and a winter to survive under snow, a stock of living food is worth the effort of making one.
Human relevance is routinely overstated. A bite can be painful and cause local swelling but is not dangerous. Meanwhile the shrew is a substantial predator of forest invertebrates and appears to influence populations of some insect pests, though how much of that effect persists across a whole season, and how it compares with other litter predators, has not been well quantified.