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.

Syringe and COVID-19 vaccine vial on top of a stock chart

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.