It seems to be a foregone conclusion that at least one COVID-19 vaccine will be available by sometime next year. Twenty-six vaccine candidates are currently in clinical testing with more likely on the way. Six candidates are already in late-stage clinical trials.

But what if the optimistic projections turn out to be wrong? Here are three large-cap stocks that should soar if coronavirus vaccines flop. 

A target with multiple arrows that didn't hit anywhere on the target

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1. Gilead Sciences

Gilead Sciences' (NASDAQ:GILD) remdesivir demonstrated the potential to improve the prospects for hospitalized patients with COVID-19 to recover more quickly in phase 3 clinical studies. The antiviral drug is available in the U.S. under an emergency use authorization (EUA) granted by the FDA and has been approved by regulatory agencies in Europe and Japan. 

The big biotech stands to make in the ballpark of $3.5 billion this year from sales of remdesivir. However, there are some questions about how much money Gilead will make over the long run from remdesivir once coronavirus vaccines are available.

Any delay in the approvals of COVID-19 vaccines would almost certainly boost sales for remdesivir. Gilead's revenue would be even higher if clinical studies evaluating an inhaled version of the drug are successful. With potentially billions of dollars in extra revenue, the biotech stock would be a sure-fire winner should COVID-19 vaccine candidates stumble in clinical testing.

2. Eli Lilly

Eli Lilly (NYSE:LLY) hasn't won regulatory approval or EUA for any of its investigational COVID-19 therapies so far. But that could change in the not-too-distant future.

The big drugmaker began a phase 3 clinical study in June evaluating arthritis drug Olumiant in treating COVID-19. Another study of the drug in combination with Gilead's remdesivir is being conducted by the National Institutes of Health (NIH).

Lilly recently started a phase 3 study of experimental antibody therapy LY-CoV555 in preventing COVID-19 in long-term care facilities. The NIH also just kicked off another late-stage study featuring the therapy. The company is also evaluating the candidate in treating hospitalized patients with COVID-19 and treating patients in ambulatory settings in earlier-stage studies. In addition, Lilly is preparing to advance antibody therapy candidate LY-CoV016 into the next stage of clinical development after obtaining positive results in a phase 1 study.

There's no guarantee that all of these candidates will be successful. But serious problems for COVID-19 vaccines would likely translate to increased interest in Lilly's coronavirus programs -- and provide a solid catalyst for the pharma stock.

3. Abbott Labs

Abbott Labs (NYSE:ABT) made headlines earlier this year with the launch of its COVID-19 diagnostic test for its ID NOW platform. The test can deliver positive results in as little as five minutes and negative results in around 13 minutes. However, Abbott offers more than one COVID-19 test.

As of July 17, 2020, Abbott had shipped 12.6 million COVID-19 antibody tests that run on its Architect and Alinity systems. It had shipped 4.5 million molecular lab novel coronavirus tests that run on its m2000 and Alinity m systems. And it had shipped 5.3 million of its rapid ID NOW tests.

If safe and effective COVID-19 vaccines become available in the near future, the demand for COVID-19 testing should fall off. Granted, there would still be a need for some testing such as for ongoing monitoring and tracking of how well vaccines are protecting against the novel coronavirus. But the needs for COVID-19 tests would definitely be lower than it is now.

However, if vaccine candidates flop, the demand for COVID-19 testing -- including antibody testing -- would be much greater and arguably more important than ever. Abbott would be a prime beneficiary.

Good news

The good news for the world is that the likelihood all of the COVID-19 vaccine candidates will fail is very low. There's a better chance that you'll get struck by lightning in your lifetime than there that none of the experimental vaccines win regulatory approval.

Here's even more good news: Each of the three large-cap stocks mentioned should still be big winners with COVID-19 vaccines on the market.

Gilead's growth prospects look strong with its HIV franchise and pipeline, which notably includes potential blockbuster immunology drug filgotinib. Lilly continues to fire on all cylinders with its cancer, diabetes, and immunology drugs. Abbott's Freestyle Libre 2 continuous glucose monitoring system, along with several other products, should keep the healthcare giant's momentum going.

All three of these stocks are attractive -- regardless of what happens on the COVID-19 vaccine front. 

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.