It definitely is. I suggest you look up what a "perfect" vaccine is, and how they work. That's what most of the ones that have eradicated diseases are. They allow the body to completely eradicate and prevent infection and transmission. That's what leads to herd immunity.

Leaky vaccines work the same way antibacterial soap did to create MRSA. They leave enough virus present to mutate to evade the mechanism originally intended to fight against it, so only the most robust mutations remain.