Peppy Wrongnozzle at Westguard Keep has suggested that you take her Peppy's Special Mix and administer it to the Dragonflayer Vrykul Prisoner to witness its results.
1x Peppy's Mix Administered To The Vrykul Prisoner
Voila, inshtant plague vacshine!
But I sure as heck am not going to try thish on myself. And I know you don't want to be my tesht shubject!
Oh, I've got... I've got an idea!
We've got a vrykul prishoner being held down in the cells under the keep. Why don't you take thish mix I whipped up down there, and get that giant to drink it ...hic?!