Many investors have eagerly followed the fast-paced achievements of companies developing COVID-19 treatments and vaccines. Gilead Sciences (NASDAQ:GILD) and Novavax (NASDAQ:NVAX) are two of the companies at the forefront of these efforts.

Both biotech stocks have been winners so far in 2020. But Novavax's year-to-date gain of more than 1,200% makes Gilead's 15% gain look tiny by comparison. Which coronavirus-focused stock is the better pick for long-term investors? Here's how Gilead and Novavax compare.

$100 bill with Ben Franklin wearing a mask

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The case for Gilead Sciences

With Gilead's announcement of its latest results on Monday, the company's antiviral drug remdesivir has now proven successful in three phase 3 clinical studies targeting COVID-19. Remdesivir isn't a miracle drug, but it seems likely to become the standard of care in treating the novel coronavirus disease.

So far, remdesivir is only approved in Japan. In the U.S., it's available through the Food and Drug Administration's Emergency Use Authorization program. Gilead hasn't officially stated its timeline for seeking FDA approval of the drug, but it seems highly likely that the biotech will move sooner rather than later.

Although remdesivir could become a blockbuster for Gilead, it's not the main reason to like the stock. The company's HIV franchise arguably deserves that honor. Gilead continues to dominate the HIV space, with Biktarvy on track to become the best-selling HIV drug ever. The biotech's pipeline also includes a promising long-acting HIV candidate in phase 2 studies that just might be able to dethrone Biktarvy down the road.

Gilead has also become a major player in oncology. In addition to Yescarta, Gilead has another promising CAR-T therapy in phase 2 testing with KTE-X19. The company's acquisition earlier this year of cancer-focused biotech Forty Seven and its partnership with Arcus Biosciences could set Gilead up for future oncology successes.

In addition, Gilead hopes to claim its share of the huge immunology market. The biotech awaits U.S. and European approvals for filgotinib in treating rheumatoid arthritis. Gilead and its partner, Galapagos, are evaluating filgotinib in treating other immunological indications as well.

Meanwhile, Gilead's dividend stands as another big plus for investors interested in the stock. The company has increased its dividend payout by 58% since initiating the dividend program in 2015. Gilead's dividend currently yields close to 3.5%.

The case for Novavax

In late February, Novavax announced that it was entering the race to develop a COVID-19 vaccine. The biotech said at the time that it was evaluating multiple candidates, and would select the most promising one to advance into an early-stage clinical study by the end of spring 2020.

Novavax did just that, starting a phase 1 study evaluating its COVID-19 vaccine candidate NVX-CoV2373 last week. It hopes to report results from this early-stage study in July, and move quickly into phase 2 testing if all goes well.

Funding the development of NVX-CoV2373 shouldn't be a problem. Novavax has received a commitment from the Coalition for Epidemic Preparedness Innovations (CEPI) to invest up to $388 million in the clinical testing and manufacturing of its COVID-19 vaccine candidate.

Meanwhile, Novavax has another pipeline candidate that could be a huge winner. The biotech reported positive results in March from a phase 3 study of experimental flu vaccine NanoFlu. The nanoparticle-based vaccine went head-to-head against Sanofi's Fluzone Quadrivalent, and came out on top.

NanoFlu has to win regulatory approval first before going to market. But assuming Novavax gains approval, it should be on a path to generate strong sales. One Wall Street analyst even thinks that NanoFlu could achieve peak annual sales of $1.7 billion.

Novavax's vaccine candidate ResVax, for respiratory syncytial virus (RSV), has flopped in a couple of late-stage clinical studies. However, the company still believes that ResVax has potential and is designing new clinical studies that could lead to a pathway for approval down the road.

The better coronavirus stock?

Which of these biotech stocks is the better pick? If you're just looking at their respective coronavirus programs, Gilead is certainly the safer choice. Remdesivir has already demonstrated at least modest levels of success in multiple late-stage studies, while Novavax's COVID-19 vaccine is only in early-stage testing.

Gilead is actually the safer pick, period. The company already generates strong cash flow and profit. It pays a dividend. And it has multiple drugs and pipeline candidates that could drive growth.

On the other hand, Novavax has more room to run if it's successful. With a market cap of around $3 billion, Novavax stock would likely generate explosive returns if its COVID-19 vaccine proves to be safe and effective.

So which stock is the better one to buy depends on your investing style. More conservative investors should like Gilead, while more aggressive investors should find Novavax appealing.