If you thought the market was crazy about vaccine stocks this year, just wait until 2021. As coronavirus vaccines are distributed to the public and a slew of companies prepare to report new revenue from sales, 2020's winners could go big yet again.

Novavax (NASDAQ:NVAX) is one such stock. The company has gained about 3,130% year to date. It probably won't grow by that much next year, but that doesn't mean new investors are too late to enjoy significant gains. In my view, there are four solid reasons why Novavax will be worth a buy next year.

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1. We'll get key efficacy data about NVX-CoV2373 soon

Novavax's coronavirus vaccine candidate is the project that put the company on the map. The company is on the verge of initiating phase 3 clinical trials of NVX-CoV2373 in the U.S. and Mexico, and its U.K.-based phase 3 trial just completed its enrollment. The U.K. trial could deliver preliminary results as early as the first quarter of next year. If the vaccine candidate is shown to be effective and safe, it'll boost the market's appraisal of the stock enormously, not to mention its revenue once it's commercialized. Currently, Novavax's trailing revenue is just over $204 million, none of which is from recurring sales. Investors may want to wait for the study's interim data readout before buying shares, just to be safe.

2. NanoFlu inches closer to approval

In March, the company successfully concluded its phase 3 clinical trials of the NanoFlu vaccine for seasonal influenza in older adults. That vaccine candidate was effective than Fluzone, the current leading product in that indication. The company still has some work to do, though. Specifically, it needs to manufacture enough doses to perform a lot-to-lot consistency trial so that regulators can confirm that the product is uniform. Once that's done, it'll be able to submit the product to the FDA for final approval.

Assuming that NanoFlu gets a green light from the regulator, it will be Novavax's first source of recurring revenue, and its stock price should jump as a result.

3. The Matrix-M adjuvant

Manufacturing the active ingredients of vaccines can be expensive. Plus, sometimes vaccines alone don't give the immune system enough of a boost to confer protection against a disease.

Both of those issues can be addressed by the use of adjuvants -- additives that increase a vaccine's effectiveness by stimulating a stronger, more durable immune response.

Novavax's adjuvant is called Matrix-M, and it's a critical component in both its coronavirus vaccine and NanoFlu. In both contexts, it should increase the competitiveness of the products from an economic perspective. With Matrix-M in the mix, each dose can use a smaller quantity of the actual vaccine, cutting overall manufacturing costs and increasing the number of doses that can be produced. For mass-scale immunizations like the one that will be required to end the current pandemic, those are especially useful features..

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4. Profits are probably right around the corner

It's entirely possible that both NanoFlu and NVX-CoV2373 will be approved for sale in 2021. While neither result is guaranteed, if they do reach the market, Novavax will be rolling in revenue to a degree it has never experienced before. Thanks in part to the U.S. government funding its coronavirus project to the tune of $1.6 billion, its profit-making potential is quite high.  

Novavax's valuation has ballooned since the start of 2020 as the market priced in those anticipated future earnings. Presently, its forward price-to-earnings (P/E) ratio is just over 8, which is quite low in comparison to the biotech industry's average of 30.21. So, even after its price spiked this year, it may not be overvalued based on its predicted earnings.

In 2021, we will get a much clearer picture of just what those earnings will look like. And, assuming everything goes well, the company will have at that point proven its vaccine-making capabilities, not to mention the merit of Matrix-M. For investors, proven science plus growing earnings will make the stock even more attractive.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.