The timeline looks scary, it looks like it took about a decade to introduce a regulation that would help protect the vultures (and humans).
> By the mid-1990s, the 50 million-strong vulture population had plummeted to near zero (...) Since the 2006 ban on veterinary use of diclofenac, the decline has slowed in some areas, but at least three species have suffered long-term losses of 91-98% (...)
Wikipedia claims that before this, a vulture species "was thought to be the most abundant large bird of prey in the world"[1].