Genentech, part of the Roche Group (SIX:RO) (SIX:ROG) (OTCQX:RHHBY), said on Monday that the US Food and Drug Administration (FDA) has approved a supplemental New Drug Application (sNDA) for influenza medicine Xofluza (baloxavir marboxil) as a treatment to prevent influenza in people aged 12 years and older following contact with an infected person.

Xofluza is the first single-dose influenza medicine approved for post-exposure prophylaxis.

The drug is already FDA-approved to treat acute uncomplicated influenza in people 12 years of age and older who have had influenza symptoms for no more than 48 hours and who are otherwise healthy or at high risk of developing influenza-related complications.

The FDA's approval was based on the Phase III BLOCKSTONE study, which showed a statistically significant prophylactic effect on influenza after a single oral dose in people exposed to an infected household contact. The proportion of household members aged 12 years and older who developed influenza was 1% in participants treated with Xofluza and 13% in the placebo-treated group.

Genentech is also working on a path forward with the FDA for a potential indication for Xofluza as a treatment for acute uncomplicated influenza in otherwise healthy children (one to 12 years of age) and for the prevention of influenza in the same age group who have been exposed to influenza.