Without a doubt, the launch of Gilead Sciences' (NASDAQ:GILD) hepatitis C drug Sovaldi has been stellar. While very early, the drug has performed better than Vertex Pharmaceuticals' (NASDAQ:VRTX) Incivek, which reached $1 billion in sales in less than a year after it launched in 2011.

The big question is whether Gilead can keep the momentum going. Its all-oral cocktail that includes Sovaldi is under review at the Food and Drug Administration, which should make it more appealing than the current regimen that requires many patients to also inject peginterferon, which has nasty side effects.

Unfortunately Gilead isn't the only company working on an all-oral concoction. AbbVie (NYSE:ABBV) is hot on Gilead's tails with its own all-oral cocktail that should be submitted to the FDA in the second quarter.

Gilead and AbbVie will ultimately be battling for an ever-shrinking population of patients, because once a patient is cured, he or she no longer needs the medication. Gilead estimates there could be as many as 4.1 million people in the U.S. infected by hepatitis C, but more than half of them don't even know they're infected.

In the video below, Fool contributor Brian Orelli and health-care bureau chief Max Macaluso discuss the ever-changing dynamics in the hepatitis C space.

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