New York CNN Business  — 

Shares of American biotech firm Gilead Sciences rose nearly 5% Monday after an official from the World Health Organization said that Gilead’s drug remdesivir is showing signs that it may be able to help treat the deadly coronavirus.

Gilead Sciences (GILD) was the second-best performing stock in the S&P 500 and was just one of two stocks in the Nasdaq-100 that was trading higher on Monday, when the Dow plunged more than 1,000 points due to fears about the disease spreading to Italy, South Korea and Iran.

“There is only one drug right now that we think may have real efficacy and that’s remdesivir,” Bruce Aylward, an assistant director-general of the World Health Organization (WHO), said at a press conference in Beijing.

WHO officials added that clinical trials for remdesivir in humans are now taking place and results could be available within weeks.

Gilead Sciences confirmed in an e-mail to CNN Business that that it is working with health authorities in China on two trials for patients who have been infected with Covid-19, the official name of this particular strain of coronavirus.

“The two studies – one in patients with severe disease and another in patients with moderate disease – are currently enrolling participants and we anticipate results in April,” the Gilead Sciences spokesman said.

Gilead Sciences also said earlier this month that it has been working with Chinese health authorities to see if remdesivir, an experimental drug that has been used to treat the Ebola virus, can combat coronavirus symptoms.

The company also said in a statement a few weeks ago that remdesivir has demonstrated some success in treating MERS and SARS, two viruses similar to the Wuhan coronavirus, in animals.

Gilead Sciences is not the only drug firm hoping to find a successful treatment for the coronavirus. Pharmaceutical giants Johnson & Johnson (JNJ) and GlaxoSmithKline (GSK) are also working on vaccines.

Biotech company AbbVie (ABBV) has said that it has seen promising results for treatment using a mixture of two of its HIV medications and Tamiflu, which is made by Swiss pharma giant Roche (RHHBF) and Japan’s Chugai Pharmaceutical Co (CHGCY).

Smaller drug companies Moderna (MRNA), Inovio Pharmaceuticals (INO) and Novavax (NVAX) are also working on treatments.