What happened Shares of Novavax (NASDAQ: NVAX) were soaring 19.1% as of 12:08 p.m. EST on Monday. This big gain came after the stock skyrocketed on Friday following its announcement of positive late-stage results for COVID-19 vaccine candidate NVX-CoV2373. Today's jump appears to be due in part to continued momentum from last week. Also, B. Riley Securities analyst Mayank Mamtani increased his price target on Novavax from $223 to $334, reflecting a 51% premium to the stock's closing price on Friday. So what It's impossible to determine how much of today's gain for Novavax stemmed from Mamtani's bullish view on the biotech stock. However, the underlying reasons for his optimism appear to be on point. Image source: Getty Images. Mamtani wrote to investors that Novavax should have "significant competitive differentiation" in the COVID-19 vaccine market. The high efficacy for NVX-CoV2373 and its logistical advantages (including no ultracold storage requirements) should help make it a big commercial winner, assuming the vaccine secures regulatory authorizations. The analyst also pointed out that Novavax has another vaccine candidate that has a lot of potential. The company reported positive late-stage results for experimental flu vaccine NanoFlu last year. Mamtani expects the biotech will be able to gain significant market share in the fast-growing COVID-19 and flu vaccine markets. Now what There are two key milestones to watch with Novavax now. First, the company should be in a strong position to soon win authorization for NVX-CoV2373 in the U.K. Second, Novavax is conducting another late-stage study of the vaccine in the U.S. and Mexico. Results from that study should be available within the next few months. 10 stocks we like better than NovavaxWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now… and Novavax wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of November 20, 2020 Keith Speights has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source