Unofficial Skyrim Special Edition Patch

In examining the scripts involved and the various Disease spells involved, it's been determined that when a player first changes into a vampire that the change does not process anything but the basic vanilla diseases. For this, we added a script call after the vanilla list that will invoke a Cure Disease spell in the same manner the werewolf scripts use when you transform into a werewolf.

Werewolves already have a generic Cure Disease call being made so they need no adjustment in this part, and as a result of how they designed this part, it will cover any disease added from any source.

With the above in mind, the addition to the vampire script being made will also mean becoming one will properly cure diseases added from other sources. This includes DLCs and mods made by others.

Aside from that, all Survival diseases are set up as the same kind of disease spells as everything else. So if you are contracting these diseases AFTER you've become either a vampire or a werewolf, that's an engine bug Bethesda will need to be fixed. Since that seems highly unlikely based on the evidence and testing that's been done, we consider this issue to be resolved with the scripting fixes.

If this should turn out not to be the case, the issue will need to be reported to Bethesda rather than us.