It is very hard for me to see how anyone would/could interpret the spell where you didn't get afflicted with the disease on turn one.
Your touch inflicts disease. Make a melee spell attack against a creature within your reach. On a hit, you afflict the creature with a disease of our choice from any of the one described below. At the end of each of the target’s turns, it must make a Constitution saving throw. After failing three of these saving throws, the disease's effects last for the duration, and the creature stops making these saves. After succeeding on three of these saving throws, the creature recovers from the disease, and the spell ends.
Since this spell induces a natural disease in its target, any effect that removes disease or otherwise ameliorates a disease’s effects apply to it.
On a hit you are afflicted, seems straight forward to me.
After three successful saves you recover from the disease, you have to be suffering some effect to recover from for this part to make sense.
I know it is OP as all get out and trivializes legendary monsters once you touch them with it, but those things don't make another reading of the spell any more valid. D&D has always had save or suck/die spells and still does, this one spell just makes that legendary monster auto save thing kinda pointless.
