The fierce battle over the hepatitis C space continued to intensify today, as the market received a huge amount of clinical trial data news, from Gilead (NASDAQ:GILD), Bristol-Myers Squibb (NYSE:BMY), and now, Merck (NYSE:MRK). Merck marks the newest entrant to the field with an all-oral regimen for genotype 1, and with its cure rate nearly on par with Gilead's at 98% after 12 weeks, and its treatment also consisting of a single pill per day, this could spell dangerous new competition for Gilead and its drug Sovaldi.

In this video, Motley Fool health care analyst David Williamson takes a look at Gilead, the big dog in this space, and compares Sovaldi with Merck's drug. David highlights all the reasons that this may represent a competitive threat down the road, but says that in the short term, the far greater risk to Sovaldi may be the pushback the drug is receiving due to its extremely high cost.