Baloxavir Helps Prevent Flu in Exposed Household Contacts

By Kelly Young

Edited by Susan Sadoughi, MD, and André Sofair, MD, MPH

Postexposure prophylaxis with baloxavir lowers the risk for acquiring influenza among household contacts of influenza patients, according to an industry-funded study in the New England Journal of Medicine. Baloxavir, a polymerase acidic protein endonuclease inhibitor, is currently approved to treat influenza.

In Japan, roughly 750 household contacts of patients with lab-confirmed influenza treated with antivirals were randomized to receive either a single oral dose of baloxavir or placebo. Two thirds of the contacts were unvaccinated against influenza. Nearly all the initial infections were from influenza A viruses.

Over 10 days' follow-up, the primary endpoint — symptomatic, lab-confirmed influenza among contacts — occurred significantly less often with baloxavir than placebo (2% vs. 14%). Baloxavir was efficacious across age groups but was somewhat less efficacious in contacts under age 12 (adjusted risk ratio, 0.3) than in those 12 and up (ARR, 0.1).

An editorialist concludes: "This trial adds baloxavir to other antiviral agents (i.e., the neuraminidase inhibitors oseltamivir and zanamivir) that have shown efficacy in reducing the transmission of influenza virus in households when used for early treatment in index patients and for postexposure prophylaxis in their contacts."