Is it too late to make money by investing in the stocks of companies battling the novel coronavirus? Not at all. Despite the successful flattening of the curve of new COVID-19 cases in many countries and U.S. states, the pandemic is far from over. And that means the companies with successful COVID-19 diagnostic tests, treatments, and vaccines could deliver more impressive growth in the future than they are now.

Which are the best coronavirus stocks to buy in 2020? If you've got $500 to invest, here are three top picks that are leaders in the fight against COVID-19.

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1. Abbott Labs 

Abbott Labs (NYSE:ABT) ranks as one of the biggest companies making COVID-19 diagnostic tests. Its test that runs on the ID NOW platform remains the fastest COVID-19 diagnostic test on the market, with positive results available within five minutes.

This test has been the center of some controversy recently with allegations that it frequently missed diagnosing COVID-19. However, Abbott announced interim results last week from an ongoing clinical study that showed high levels of accuracy in providing both positive and negative results for exposure to the novel coronavirus disease.

Abbott currently sells multiple COVID-19 diagnostic tests in addition to the one that runs on its ID NOW platform, including a COVID-19 antibody test. More importantly, the company claims several growth drivers that are even bigger than its coronavirus-focused products, notably including its Freestyle Libre continuous glucose monitoring (CGM) system and Alinity family of lab diagnostics systems.

For investors who like steady and reliable dividend stocks, Abbott Labs is likely to be very attractive. The healthcare giant has paid a dividend every quarter since 1924. It has also increased its dividend for 48 consecutive years. Abbott's dividend currently yields north of 1.5%.

2. Gilead Sciences

Gilead Sciences' (NASDAQ:GILD) remdesivir has been near the top of the list for treating COVID-19 for several months even though there was uncertainty about the drug's efficacy. Now, that uncertainty appears to be largely removed. Last week, the National Institute of Allergy and Infectious Diseases (NIAID) published results from its late-stage study of remdesivir that supported the use of the drug in treating hospitalized patients with COVID-19.

It won't be surprising for combination therapies including remdesivir to demonstrate even more impressive results down the road. Gilead seems poised to have another blockbuster drug on its hands, although the big biotech's reluctance to charge too much for remdesivir could mean that it won't make the huge profits that some might expect.

Remdesivir is just a bonus for investors who consider buying shares of Gilead, though. The real crown jewels are the company's HIV franchise and its pipeline. Biktarvy is on track to become the best-selling HIV drug of all time. Gilead is awaiting approval of filgotinib in treating rheumatoid arthritis. If approved, some analysts think the drug could generate peak annual sales of $4 billion or more.

Like Abbott Labs, Gilead offers an attractive dividend. Although the company only initiated its dividend program in 2015, it has boosted its dividend payout by 58% over the last five years. Gilead's dividend yield of 3.7%, combined with its growth prospects in HIV, cancer, and immunology, should enable the stock to deliver solid total returns over the long run.

3. Novavax

To be sure, Novavax (NASDAQ:NVAX) is the riskiest of these three coronavirus stocks. The small biotech doesn't have an approved product on the market yet. And it's a little behind a few rivals in beginning clinical testing of its COVID-19 vaccine candidate.

But Novavax does have a promising candidate for immunizing against the novel coronavirus. It's so promising that the Center for Epidemic Preparedness Innovations (CEPI) is investing up to $388 million to fund Novavax's experimental COVID-19 vaccine NVX-CoV2373. That's the highest amount CEPI has ever committed to a single program.

Novavax hopes to report phase 1 results for NVX-CoV2373 in July. If all goes well, the company will quickly move into phase 2 testing. It will also begin to ramp up production of the vaccine in parallel with its clinical studies.

In addition to its promising coronavirus vaccine candidate, Novavax has another potentially big winner in its pipeline. The biotech stock has soared in 2020 thanks in large part to the success of its flu vaccine candidate NanoFlu in late-stage clinical testing. One analyst thinks that NanoFlu could reach peak sales of $1.7 billion. With its market cap currently below $3 billion, Novavax should have a lot of room to run.