Japan's Shionogi & Co Ltd and Swiss drugmaker Roche won US Food and Drug Administration (FDA) approval for their flu treatment, the first new flu drug approved by the agency in nearly 20 years.
Xofluza was approved to treat acute uncomplicated influenza, a contagious respiratory illness caused by influenza viruses, in patients 12 years of age and older who have had symptoms for more than two days, the FDA said.
"This is the first new antiviral flu treatment with a novel mechanism of action approved by the FDA in nearly 20 years," FDA Commissioner Scott Gottlieb said in a statement.
"While there are several FDA-approved antiviral drugs to treat flu, they're not a substitute for yearly vaccination."
An exceptionally harsh US flu season last year resulted in more than 900,000 people getting hospitalised and more than 80,000 deaths, according to estimates.
Xofluza will be marketed outside Japan and Taiwan by Roche, which also makes commonly prescribed flu medication Tamiflu. Shionogi will retain co-promotion rights in the United States.
The drug could help bolster Roche's position in the influenza drug market as it faces competition from generic medicines.
Sales of Roche's Tamiflu tumbled 33 per cent to 535 million Swiss francs (US$537 million) in 2017, as cheaper generics muscled in.
Xofluza was approved by the Ministry Of Health, Labour And Welfare in Japan for the treatment of influenza strains early this year.