Nynaeve can Heal the taint. This isn't a new ability despite what some people think.

EoTW (Dragonmount) - "A pity for you... that one of your Sisters is not here. I was never very skilled at Healing... but even one of them could only give you a few lucid minutes."

Rand is shocked that Nynaeve can Heal the taint and he says that even in his Age, diseases of the mind were very hard to cure. That said, Lews Therin has no knowledge of the taint and the efforts to cure it, considering he was the first man ever to go insane.

It seems that very gifted Healers could probably remove the effect from a tainted male just like Nynaeve did. The problem is that the taint still existed on saidin, and within minutes of being Healed they would become tainted again. Its more than likely that they were even more open to the taint after being tainted once, and thus their ability to buy the man only a few lucid minutes. It thus became a self-limiting and futile exercise. In Nynaeve's case it's a wonderous cure, and in their case a silly one considering the disease was waiting to reinfest the man again.