What: Shares of Novavax (NASDAQ:NVAX), a clinical-stage vaccine development company focusing on an array of respiratory and infectious diseases, surged 16% in May, according to data from S&P Global Market Intelligence. The reason for Novavax's decisive move higher can be traced to three notable catalysts.

So what: Arguably, the best news for Novavax came a little more than a week earlier when the Food and Drug Administration granted Fast Track designation to Novavax's experimental RSV F-Protein vaccine for the protection of older adults ages 60 and up. RSV, or respiratory syncytial virus, affects about 900,000 people in the U.S. annually, and it ultimately results in an estimate 16,000 deaths in older adults each year. RSV F is currently being examined in an 11,850-person trial that became fully enrolled this past December. Data from this trial should be available by the third quarter, and if it looks good, the Fast Track designation could speed up the process by which Novavax gets its drug on the FDA's desk for review.

Secondly, Novavax received a nice little boost in mid-May when investment money managers were required to file form 13F with the Securities and Exchange Commission. In those filings we discovered that Soros Fund Management, headed by billionaire George Soros, picked up 30,300 shares of Novavax. What's unique about Soros is he's been taking a notably bearish position on U.S. equities over the past quarter, so to see him bullish on Novavax is especially intriguing.

Finally, Novavax is still tinkering with the idea of creating a Zika virus vaccine. Although fewer than 1,000 Zika cases have been reported in the U.S., we've witnessed millions reported in South America (mainly Brazil). The disease itself often has unpleasant side effects that last for a few days to a week in those it infects, but it can also, in rare instances, lead to microcephaly in newborns or Guillain-Barre syndrome in adults. The fear and uncertainty surrounding Zika has definitely put some pep in the step of Zika virus researchers.

Now what: Most eyes might be on a potential Zika cure, but smart investors are going to be paying close attention to the RSV F protein results in the upcoming quarter. A successful trial and subsequent FDA approval would net Novavax some much needed recurring revenue. More importantly, analysts project that with only a handful of preventative options available to older adults for RSV, Novavax's vaccine could top out above $1 billion in annual sales by 2022. It's not uncommon for biotech companies to trade at a multiple or two or three times the peak sales potential of their lead drug. Thus, with Novavax valued at less than $1.7 billion, there could still be substantial upside if the phase 3 data looks good.