Novavax (NVAX 2.31%) got off to a fantastic start this year. By early February, the stock had soared more than 180% year to date. But it hasn't been such a great story since then. Novavax's shares have fallen around 50% from the high set a month ago.

I don't think it's time to throw in the towel on the biotech by any means. Here are three reasons to buy Novavax stock after its huge pullback.

Gold dollar sign surrounded by coronavirus

Image source: Getty Images.

1. Near-term catalysts

The only thing struggling biotech stocks need to turn things around is a positive catalyst or two. And Novavax probably has several of them on the way.

In late January, Novavax reported great results from a late-stage study of COVID-19 vaccine NVX-CoV2373 conducted in the U.K. The company stated in its Q4 update last week that it expects to file for U.K. authorization of the experimental vaccine in early second quarter. It seems likely that NVX-CoV2373 will win this authorization, which should provide a nice boost to Novavax's share price.

An even bigger catalyst could come soon after that. If the U.S. Food and Drug Administration (FDA) allows Novavax to file for U.S. emergency use authorization (EUA) based on its U.K. data, the biotech's COVID-19 vaccine could become available to Americans in May. 

What happens if the FDA doesn't permit Novavax to use its U.K. data as the basis for its EUA filing? No worries. The company recently completed enrollment in its late-stage study of NVX-CoV2373 in the U.S. and Mexico. If it's required to use data from this study for its submission, EUA in the U.S. should still be on the way by June or July.

2. Attractive valuation

Thanks to the big sell-off for Novavax, the company's market now stands below $12 billion. I view this as an attractive valuation.

The consensus among Wall Street analysts is that Novavax will make nearly $5 billion in sales this year. That estimate doesn't seem farfetched at all, in my opinion. The company already has supply deals lined up for around 300 million doses. In addition, the company has an agreement with the Serum Institute of India for 1.1 billion doses.

Novavax's current market cap and that revenue target gives the company a forward price-to-sales (P/S) multiple of 2.4. By comparison, BioNTech currently trades at 2.7 times expected sales. Moderna's forward P/S multiple is close to 3.1.

Sure, both BioNTech and Moderna have larger pipelines than Novavax does. However, Novavax has another candidate that's already sailed through late-stage testing while the other two companies don't have a candidate waiting in the wings in a similar position.

3. Long-term opportunities

That leads us to arguably the best reason to buy Novavax stock: The biotech's long-term prospects. NVX-CoV2373 is an important component to those prospects. But so is Novavax's other lead candidate, flu vaccine NanoFlu.

Immediately prior to the COVID-19 pandemic, NanoFlu ranked as the primary reason behind investors' interest in Novavax. In March 2020, the company reported overwhelmingly positive results from a late-stage study of the flu vaccine in a head-to-head comparison against Sanofi's FluZone Quadrivalent. 

Novavax is looking at several possibilities for commercializing NanoFlu. These include featuring it as a combination vaccine with NVX-CoV2373, with its experimental respiratory syncytial virus (RSV) vaccine, and perhaps even putting all three vaccines together.

In addition, the biotech plans to initiate a clinical study evaluating candidates targeting new coronavirus variants, including a bivalent vaccine, in mid-2021. These efforts could position Novavax well in the COVID-19 vaccine market going forward.

Novavax still faces risks that its vaccines won't ultimately win authorization or approval. However, I don't think those risks are too worrisome considering the solid late-stage results reported for both NVX-CoV2373 and NanoFlu. My prediction is that the stock will finish the year valued well above its current price.