The % health rune has the exact same issue I mentioned for Juggernaut on Vlad.
Both work with W's bonus health, neither work with Vlad's passive. Funny that the patch preview highlighted Vlad's passive when a % health rune doesn't actually work with his passive.
Edit: For an Easy check, Kindlegem with one Tier 3 % health seal (+0.5%) gives 201 health, as expected. Vlad's passive increases by exactly 5 AP when it should read 5.02 or 5.03 (201/40=5.025, but Vlad's Passive only displays 2 decimal places).