Weak Vampires?

There have been many variations on vampires in written fiction and
visual media. We've encountered good vampires, bad vampires, ones that
are susceptible or not to garlic, crosses, sunlight or wooden stakes.
Some have to be invited in, others disregard this piece of lore. Some
are fantasy creatures. Others have contracted some virus or have
altered genes. Some need human blood, others can sustain themselves on
animal blood. Some are sexy, some are ugly.

I was wondering what is the minimum requirement for still being called
a vampire. Obviously the one common theme in all vampire fiction is
that they have to drink blood. But the other recurrent theme is  that
vampires are harder to kill and they are faster and physically
stronger than ordinary humans. Vampires, in other words, are top
predators.

this in turn got me thinking: did anyone ever write about weak
vampires? frail vampires that hide in shadows and have to hunt in
groups, or use subterfuge, because they are weaker than their prey?