Xofluza Cuts Flu Transmission

The trial met its primary endpoint, showing a single, oral dose of Xofluza taken by people infected with influenza reduced the odds of untreated household members contracting the virus by 32%. For the key secondary endpoint of influenza virus transmission resulting in symptoms, Xofluza showed a clinically meaningful reduction although statistical significance was not reached. Xofluza was well tolerated, with no new safety signals identified. Results from the CENTERSTONE trial have been submitted to health authorities, including the FDA and the EMA.

The CENTERSTONE trial [NCT03969212] was a global phase III trial investigating the efficacy of single-dose Xofluza, taken within 48 hours of symptom onset, to reduce the onward transmission of influenza within households. The trial was conducted in 272 sites across the globe, with over 4,000 participants, and involved otherwise healthy patients from 5- 64 years who had been diagnosed with influenza via a polymerase chain reaction (PCR) or rapid influenza diagnostic test, known as index patients (IPs), and those within their household (known as household contacts, HHCs). The design of this randomised, placebo-controlled trial was developed with input from the US FDA and leading experts in influenza.

The primary endpoint was the proportion of HHCs  (household contacts) who tested positive for influenza within five days after the IP (index patients ) had been treated with either Xofluza or placebo (1:1 randomisation within 48 hours of symptoms onset). There was a 32% reduction in the odds of transmission (adjusted odds ratio [aOR] = 0.68 [95.38% CI: 0.50–0.93]; adjusted incidence of transmission:13.4% with placebo vs 9.5% with baloxavir; p=0.013) with Xofluza versus placebo.

For the key secondary endpoint of symptomatic transmission of influenza virus by day five, Xofluza showed a clinically meaningful reduction, although statistical significance was not reached. There was a 25% reduction in the odds of transmission resulting in symptoms (aOR = 0.75 [95.38% CI: 0.50–1.12]; p=0.155). Numerical reductions were observed for additional endpoints, including transmission at the household level and transmission up to day 9.

“This trial is the first to demonstrate an antiviral effect that reduces transmission of influenza viruses within a household. This result may potentially have broad-reaching implications for public health,” said Dr.  Levi Garraway,  Roche’s Chief Medical Officer and Head of Global Product Development. “This publication reminds us of the ongoing societal need for solutions that can help ease the burden of influenza on society.”

See citation-  Monto AS,  Kuhlbusch, K  et al. Efficacy of Baloxavir Treatment in Preventing Transmission of Influenza N Engl J Med 2025;392:1582  DOI: 10.1056/NEJMoa2413156