A recent Phase IIIb multicountry study has demonstrated that a single oral dose of an antiviral flu treatment can significantly reduce the transmission of influenza within households, offering a potential new strategy for healthcare professionals to mitigate spread during flu season.
The study enrolled 1,457 influenza-positive index patients aged 5 to 64 years and 2,681 household contacts across multiple influenza seasons (2019–2024). Participants were randomly assigned to receive either a single dose of the antiviral baloxavir or a placebo within 48 hours of symptom onset. The primary endpoint evaluated the transmission of laboratory-confirmed influenza from the index patient to household contacts by day 5.
Results showed that flu transmission to household contacts was significantly lower in the baloxavir group (9.5%) compared to placebo (13.4%), translating to an adjusted relative risk reduction of 29% (95.38% CI, 12 to 45; P=0.01). These findings suggest that early intervention with baloxavir may help curb the spread of influenza within close-contact settings, an area where prior treatments like neuraminidase inhibitors have shown limited evidence of impact.
While the incidence of symptomatic transmission was also lower in the baloxavir group (5.8%) versus placebo (7.6%), this difference did not reach statistical significance (P=0.16). Importantly, no drug-resistant viruses were detected among household contacts, though resistance emerged in 7.2% of treated index patients.
For healthcare providers managing influenza outbreaks, these findings highlight a promising role for baloxavir in reducing viral spread, potentially enhancing existing infection control measures. No new safety concerns were identified during the study period, supporting the safety profile of the single-dose treatment.
As influenza continues to pose seasonal challenges, incorporating antiviral treatments that not only address symptoms but also reduce transmission could reshape strategies for flu management, particularly in high-risk household environments.
Reference:
Ison M.G. et al. Efficacy of Baloxavir Treatment in Preventing Transmission of Influenza. N Engl J Med. 2024;390:1584-1594.
