So I found a Nether fortress, got in, found the two Blaze spawners, got hit by some Blaze fireballs, killed the Blazes and got some blaze rods and experience orbs, then went wandering in the fortress, found some Nether Warts, dug some Nether Bricks, got shot by more blazes, killing them again, being shot by some skeletons, killing them and getting some bones, and finally I saw two Wither Skeletons.
I quickly hold S to stay away from them (they are chasing me), get my nice diamond sword ready and fight...
They hit me fast and my health bar turned black and those nice hearts start leaving me. I get affected by the wither effect!
After some fight, I finally killed both of them and get the drops including a piece of stupid coal. My health is getting low (I am a coward, so I set mode to easy and I didn't die that fast) but it regenerates, thanks to my full hunger bar.
OK, end of the bedtime story, let's get to the real question: Is there any factors that prevents the wither effect from affecting me or can I reduce the effect or make them stop faster? Any potions/armor/whatever?
(The same should apply to the wither effect caused by Withers?)