Gilead Sciences (NASDAQ:GILD) is among many biotech and pharmaceutical companies working on treatments for COVID-19, the illness caused by the novel coronavirus. Where Gilead stands apart is it actually has a treatment that the U.S. Food and Drug Administration (FDA) has authorized for emergency use.

What is remdesivir?

Gilead initially developed remdesivir as part of its hepatitis C and respiratory syncytial virus (RSV) research in 2009. With the Ebola outbreak a few years later, the company explored the antiviral's potential, but other treatments produced better survival rates. Preclinical data in other coronaviruses, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), were promising, but clinical trials couldn't be conducted because it couldn't enroll enough patients as cases declined. Maintaining a strong belief in remdesivir's potential, Gilead renewed preclinical studies of the drug once COVID-19 emerged.

As a nucleoside analog, remdesivir "pretends" to be a nucleoside that occurs naturally in the virus. But instead of helping the virus replicate, this imposter interrupts the process. The drug is administered intravenously over a period of five to 10 days.

Coronavirus triage bay

Image source: Getty Images.

Does remdesivir cure COVID-19?

Remdesivir doesn't cure COVID-19, but a National Institute of Allergy and Infectious Diseases trial demonstrated the drug's ability to help patients recover faster.

Gilead-sponsored trials added to the positive data. In a phase 3 trial, Gilead studied remdesivir in hospitalized patients with moderate COVID-19 pneumonia compared with a standard of care group. According to the latest results, patients given remdesivir for a period of five days were 65% more likely to show clinical improvement on the 11th day following the start of treatment than those given standard care.

In another phase 3 study, Gilead examined the use of remdesivir in hospitalized patients with severe COVID-19. That study showed that patients taking a five-day treatment experienced about the same benefit as those on a 10-day regimen. Fourteen days after the start of treatment, more than 64% of patients in the five-day group and nearly 54% in the 10-day group had achieved clinical recovery. "Clinical recovery" means the patient no longer needs medical treatment. The study also found that patients who received remdesivir within 10 days of the first symptoms had better outcomes than those given the treatment later.

Currently, there are more than 20 recruiting or active remdesivir trials worldwide, according to ClinicalTrials.gov. Gilead has said it is donating more than 1 million doses of remdesivir to U.S. hospitals and clinical trials.

Are other COVID-19 treatments in clinical trials?

Other companies and research teams are testing possible treatments for COVID-19 in clinical trials around the world. Partners Sanofi (NASDAQ:SNY) and Regeneron (NASDAQ:REGN) are exploring the use of rheumatoid arthritis drug Kevzara with the hope it may reduce the body's inflammatory response. So far, studies have shown a possible benefit to critical patients but no benefit to patients with severe COVID-19. Testing will continue in critical patients only.

Separately, Regeneron started a clinical trial this month on an antiviral antibody cocktail for the prevention and treatment of COVID-19. The study includes four groups: patients hospitalized with the virus, non-hospitalized COVID-19 patients, uninfected people in high-risk positions like healthcare, and uninfected people who have close contact with a COVID-19 patient (such as a family member).

Researchers also continue to study the anti-malaria drug hydroxychloroquine in more than 100 clinical trials worldwide, even after the FDA revoked the treatment's emergency use authorization and several studies indicated the drug wasn't efficacious. Hydroxychloroquine sparked controversy after President Trump touted its benefits. Some took the drug without the surveillance of a doctor, resulting in serious injury or death. That's why it is essential to speak with a doctor before taking any prescription medication.

There are more than 1,300 active or recruiting clinical trials worldwide investigating therapies for COVID-19, ClinicalTrials.gov data show. Treatments involved in testing include plasma-based therapy, traditional Chinese medicine, corticosteroids, and many others.

So far, remdesivir shows great promise in treating COVID-19 patients, but there is still much more research needed before it's deemed a cure.