Roche’s investigational single-dose antiviral Xofluza showed superior efficacy in speeding up improvement of flu symptoms in people at high risk of complications, according to the company.

Roche’s Capstone-2 trial focused on adults aged 65 or older, or those with conditions such as asthma, chronic lung disease, diabetes, or heart disease.

The anti-viral medicine is approved in Japan. US regulators have accelerated their review and could make a decision by Dec 24.

Roche has partnered with Japan’s Shionogi to develop the single-dose drug, touting it as a more convenient alternative to Tamiflu’s twice-daily, five-day regimen.