Will Falconer, DVM Moderator
This is called "vaccine failure" and it's widely accepted that parvo vaccine has a failure rate around 40%! The drug reps have admitted it and the practitioners have seen it over and over again.
Homeopathic nosodes, properly used, will do far better. If you haven't listened yet, check out the Vital Animal Podcast, Episode #2, where Dr. Cooney has wiped out parvo from his practice population by giving new puppy parents parvo nosodes!