Last week, the stock market experienced its worst week since 2008. The culprit for that long-awaited correction was none other than the COVID-19 epidemic. The coronavirus keeps spreading worldwide and is threatening to become a full-blown pandemic.

According to the latest numbers from the Centers for Disease Control and Prevention (CDC), more than a dozen states in the U.S. have confirmed cases of COVID-19, and more than 10 people in the U.S. have died as a result. The World Health Organization said more than 80 countries have confirmed cases of COVID-19, and more than 3,100 people have died. No one knows how long this crisis will continue, but amid all this frenzy, some stocks have made healthy gains because of the COVID-19 outbreak. Let's talk about three of these stocks: Gilead Sciences (NASDAQ:GILD), Inovio Pharmaceuticals (NASDAQ:INO), and Moderna (NASDAQ:MRNA).

Woman walking across a street, talking on the phone and wearing a face mask.

Image source: Getty Images.

The leader in the fight against COVID-19

Over the past month, shares of Gilead Sciences are up by 22%, which compares favorably to the S&P 500, which is down by 11% over the same period. The reason? Gilead Sciences is currently leading the charge in the quest to find a treatment for COVID-19, the illness caused by the coronavirus. WHO officials anointed Gilead Sciences' remdesivir as the most promising potential treatment for the disease. Gilead Sciences originally developed remdesivir as a possible treatment for Ebola, but the drug did not prove particularly effective in treating it. 

These efforts may have not been in vain, however, as Gilead Sciences is now racing to study the efficacy of remdesivir as a treatment for COVID-19. On Feb. 26, the company announced the initiation of two phase 3 studies to investigate the efficacy of remdesivir in treating adults with COVID-19. These studies will enroll around 1,000 patients, primarily in several Asian countries, and should begin sometime this month.

In both studies, patients will take oral doses of remdisivir for five or 10 days. One of the studies will enroll 400 patients with "severe clinical manifestations," and the other will enroll 600 patients with "moderate clinical manifestations." If remdisivir proves effective at treating COVID-19, Gilead Sciences should move to the next step in the process and submit it to the U.S. Food and Drug Administration (FDA) for approval, as well as to the appropriate regulatory authorities abroad. 

Of course, the market will likely remain volatile, and shares of Gilead Sciences may eventually start moving downward. But as things stand, the company's stock has benefited from the recent developments surrounding COVID-19. 

A comparative stock chart

Image Source: YCharts

Racing to find a vaccine 

Shares of Inovio Pharmaceuticals are up by a whopping 289% over the past month, and these gains can be attributed to the company's involvement in the fight against COVID-19. Here's a timeline of several events that highlight Inovio's attempts to develop a vaccine against the potentially deadly disease:

  • On Jan. 23, the Coalition for Epidemic Preparedness Innovations (CEPI) awarded a grant of up to $9 million to Inovio to develop a vaccine for COVID-19; Inovio's shares soared by about 10% on the heels of this announcement. 
  • On Jan. 30, the company announced a collaboration with Beijing Advaccine Biotechnology to develop INO-4800 -- a potential vaccine for COVID-19 -- in China. The company's shares climbed by 11% on the news. 
  • On Feb. 13, Fox Business reported that Inovio could start testing its potential vaccine for COVID-19 as early as this summer, which sent the company's shares up by about 20%
  • Lastly, on March 3, Inovio said it could start trials for its potential vaccine against COVID-19 earlier than previously reported. The company now expects to begin trials as early as April, news that sent the company's shares soaring by 70%. 

Despite all this noise, though, Inovio has yet to start testing its potential vaccine for COVID-19, which means the company is significantly behind Gilead Sciences in this race. Still, this is one company investors will want to keep an eye on as the COVID-19 epidemic continues to make headlines. 

Focusing on mRNA technology

Moderna is a biotech company that focuses on developing vaccines using mRNA technology, which consists of delivering a set of instructions within the cell to help the body produce proteins to fight against diseases. In this spirit, the company quickly developed a vaccine for COVID-19.

On Feb. 24, the company announced that it was shipping its potential COVID-19 vaccine to the National Institute of Allergy and Infectious Diseases (NIAID) to start a phase 1 study. Moderna expects the phase 1 study to start sometime next month; meanwhile, the company's shares are up by 46% in the last month. 

Are they buys? 

While Inovio is by far the biggest winner (so far) out of these three companies, its stock remains a risky investment. The company currently has no product on the market and derives its revenue from collaboration agreements. During the third quarter, Inovio's revenue was less than $900,000, and the company recorded a net loss of about $23 million. While Inovio does have several interesting targets in its pipeline -- including potential products for head and neck cancer as well as prostate cancer -- there's no guarantee that these projects will pan out.

Similarly, Moderna has no approved product on the market and derives its revenue mostly from collaboration arrangements. The company's pipeline features a raft of potential vaccines, including mRNA-4157, a personalized cancer vaccine candidate. But it seems too early and too risky for investors -- aside for the most aggressive ones -- to invest in this company.

By contrast, Gilead Sciences presents strong prospects outside of its potential treatment against COVID-19. And while its gains over the past month haven't been nearly as impressive as those of Moderna or Inovio, Gilead Sciences is the most likely to come out a winner in the long run. Ultimately, the only one of these biotech stocks investors should seriously consider buying today is Gilead Sciences.