By drinking this, you become a melting pot for viruses!
*You gain a blanket immunity to all diseases and/or viruses, no matter how hazardous they are. Ebola? Might as well not exist! Black Plague? Don't even notice it. T-Virus? You'll be eating it's brains! You may, of course, turn this off for some viruses.
*This extends to more esoteric "viruses", like vampirism and lycanthropy. No longer do you have to worry about some asshole biting you and causing you to transform every full moon.
*You have the ability to create viruses! Anything from mundane ones like the flu, to more mystic ones such as the ones mentioned above. You may also modify already existing viruses.
*Create a virus that turns people into bimbos! Create a virus that turns everyone into immortal superhumans! Conjure a virus that makes infectees utterly loyal to you!
*By coming into contact with viruses you haven't made yourself, you gain an intimate understanding of how they work and how they may interact with other viruses. The T-Virus and a girlifying virus might create monstergirls, for example.