Novavax (NASDAQ: NVAX) has jumped from a price of $4 a share back in January to $128 a share in December. That's a huge 3,000% gain for early investors. Is now a good time to buy Novavax? The answer is absolutely -- if the company's COVID-19 vaccine has positive data from one of its pivotal trials. And I'd say, not at these prices, if the company reports unhappy news. Image source: Getty Images. Right now, the stock price is at the mercy of the company's COVID-19 vaccine. If Novavax reports 90% efficacy levels, the sky's the limit. At an $8 billion market cap, the stock could easily triple to $24 billion (still under the market cap of BioNTech). And some bulls might wonder why Novavax isn't as valuable as Moderna ($62 billion). The market opportunity for a COVID-19 vaccine is surreal. Operation Warp Speed paid $1.6 billion to obtain 100 million doses of Novavax's vaccine, pricing the drug at $16 a dose. This is a two-shot regimen, so that's only enough to vaccinate 50 million people. The price tag might be higher or lower, depending on many factors, but $16 a dose is a good starting point for a back-of-the-napkin calculation. Novavax has agreements in place to manufacture over 2 billion doses. At a price point of $16 a dose, that's $32 billion in potential revenue in 2021. The upside is incredible. And we still don't know if a COVID-19 vaccine will be a one-time event (like for the mumps) or an annual ritual (like with the flu shot). This stock will be volatile over the next several months. Positive data will send shares soaring higher. But if the vaccine doesn't work? Look out below. 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 Taylor Carmichael owns shares of Novavax. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source