WASHINGTON - The US Food and Drug Administration (FDA) on Thursday approved Gilead Sciences' antiviral drug Veklury (remdesivir) as a treatment for COVID-19.

Veklury is indicated for use in adult and pediatric patients 12 years of age and older and weighing at least 40 kg for the treatment of COVID-19 requiring hospitalization, said the FDA in a statement.

Previously authorized by the FDA for emergency use to treat COVID-19, Veklury is now the first and only approved COVID-19 treatment in the United States.

Veklury should only be administered in a hospital or in a healthcare setting capable of providing acute care comparable to inpatient hospital care, said the FDA.

"Today's approval is supported by data from multiple clinical trials that the agency has rigorously assessed and represents an important scientific milestone in the COVID-19 pandemic," said FDA Commissioner Stephen M. Hahn.

The FDA will continue to help move new medical products to patients as soon as possible, while at the same time determining whether they are effective and if their benefits outweigh their risks, he said.

The approval of Veklury was supported by the agency's analysis of data from three randomized, controlled clinical trials that included patients hospitalized with mild-to-severe COVID-19.

One randomized, double-blind, placebo-controlled clinical trial (ACTT-1), conducted by the US National Institute of Allergy and Infectious Diseases, evaluated how long it took for subjects to recover from COVID-19 within 29 days of being treated.

Results showed the median time to recovery from COVID-19 was 10 days for the Veklury group compared to 15 days for the placebo group, a statistically significant difference, according to the FDA.

Possible side effects of the drug include increased levels of liver enzymes and allergic reactions.

In parallel with the FDA approval of Veklury, the FDA also issued a new Emergency Use Authorization for the use of Veklury to treat hospitalized pediatric patients under 12 years of age weighing at least 3.5 kg, or hospitalized pediatric patients weighing 3.5 kg to less than 40 kg with suspected or laboratory confirmed COVID-19, according to Gilead.