Last year, coronavirus vaccine stocks led stock market gains. For instance, Novavax (NASDAQ:NVAX) surged more than 2,000% for the biggest increase among all stocks in all industries. With the pandemic deepening, the priority quickly became disease prevention. The U.S. government even created a program to help speed vaccines to market called Operation Warp Speed. 

Companies focusing on coronavirus treatment garnered less attention. Gilead Sciences (NASDAQ:GILD) actually fell 10% last year. That company makes remdesivir, the first FDA-approved treatment for COVID-19. Now that two vaccines have reached the market, though, some investors have shoved treatment-makers aside in favor of the companies that will bring us back to some semblance of normalcy. But as long as people continue to contract COVID-19 in 2021, and if these treatment companies' clinical trial data are positive, their stocks could climb in the New Year.

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1. Redhill

Redhill Biopharma (NASDAQ:RDHL) specializes in gastrointestinal illnesses, but has broadened its work to include infectious diseases and oncology. The company has six programs in the pipeline, including two potential treatments for COVID-19. And one of those COVID-19 programs recently produced encouraging safety and efficacy data in a phase 2 trial.

The treatment candidate, opaganib, blocks the action of sphingosine kinase-2. This is an enzyme that plays a role in viral replication. Opaganib acts on the body's response rather than on the virus itself. An advantage is that potential viral mutations are unlikely to reduce such a treatment's efficacy. Another plus is that opaganib works as an anti-inflammatory agent and an anti-viral. This is significant because the challenges of treating COVID-19 include reducing viral load and preventing the body's inflammatory response from going into overdrive.

Redhill's trial involved 40 hospitalized patients requiring oxygen. It showed that more than 52% of patients no longer required oxygen support by day 14. That's compared to 22% of patients in the placebo group. The study also showed that more than 73% of treated patients were released from the hospital by day 14. The hospitals discharged only about 55% of patients in the control group by that point. The company expects a data readout from another trial -- a phase 2/3 trial of opaganib in patients with severe coronavirus pneumonia -- this quarter. That study is enrolling 270 patients across 30 sites worldwide.

Redhill's market capitalization of just $322 million leaves plenty of room for growth. If Wall Street's average forecast is right, the shares could climb 184% in the coming 12 months. Data from the opaganib trials will be the catalyst in the near term. Beyond that, potential sales growth of the company's three commercialized gastrointestinal products could offer reason for future gains.

2. Atea

Atea Pharmaceuticals (NASDAQ:AVIR) is a clinical-stage company working on treatments for viral diseases. The company has four programs in the pipeline targeting COVID-19, dengue, hepatitis C, and respiratory syncytial virus (RSV). The COVID-19 candidate, in phase 2, is its most advanced.

AT-527, Atea's investigational coronavirus treatment, is an anti-viral agent. It's meant to hamper the action of viral RNA polymerase, an important part of the coronavirus's replication process. The idea is that AT-527 could halt viral replication. The current trial is evaluating AT-527 in hospitalized patients with moderate COVID-19. Atea expects data from that trial in the first half of this year. Also in the first half, Atea plans to launch a phase 3 trial in outpatients. Atea aims to study AT-527 as a preventative treatment in a supplemental phase 3 trial to begin in the second half of the year.

An advantage of the company's candidate is that it's easier to administer than antibody treatments. Antibodies must be administered by intravenous infusion directly into the blood. The process takes about an hour. The U.S. Food and Drug Administration has authorized two such products -- from Eli Lilly (NYSE:LLY) and Regeneron Pharmaceuticals (NASDAQ:REGN) -- so far. Atea's treatment is administered as a pill.

Roche's interest in the program is another positive. In October, Atea and Roche signed a collaboration agreement for AT-527. The big pharma company gains exclusive rights to develop and distribute the treatment candidate outside of the U.S. Roche offered Atea an upfront payment of $350 million and the possibility of milestone payments and royalties down the road.

Atea shares have doubled since their stock market debut on Oct. 30. But, if Atea's AT-527 trial results are encouraging, the stock could move higher. The COVID-19 drug market isn't crowded. And the need to infuse current treatments such as antibodies and antiviral remdesivir makes them more complicated and costly to administer than this potential oral treatment.

Will the shares soar?

If clinical trials progress smoothly, Redhill and Atea could soar in the first half of the year -- and beyond. But it's important to remember that setbacks or even failure can happen at any point in clinical trials. And that kind of negative news could seriously hurt shares of both of these biotech companies.

Redhill and Atea may be future winners of the coronavirus treatment race. But only investors comfortable with some risk should consider buying them right now.

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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.

Adria Cimino has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Gilead Sciences. The Motley Fool has a disclosure policy.