Shares of Sinovac Biotech (NASDAQ:SVA) soared as much as 50% intraday, as its hand, foot, and mouth disease (HMFD) vaccine aced a phase 3 trial. Before you get too excited over this groundbreaking vaccine's potential, watch this video, in which health-care analyst David Williamson argues why this new product may not transform Sinovac.

HMFD is a generally a mild illness with nearly all patients recovering in seven to 10 days. Even Sinovac said that over the last five years, only 500 to 900 cases have proven fatal  -- less than one tenth of one percent of all infections -- in China, a country with over 1.3 billion citizens. It may not be considered a serious enough issue to prompt widespread use of the vaccine in mainland China, where Sinovac derives virtually all of its sales.

Watch and find out what it all means for investors.