Baloxavir may prevent influenza in exposed household contacts: NEJM
Japan: Single-dose of Baloxavir may help in the prevention of influenza in household contacts of patients with the flu, a recent study in the New England Journal of Medicine has found.
Baloxavir marboxil (baloxavir), a polymerase acidic protein endonuclease inhibitor, is currently approved for influenza treatment. It has clinical efficacy in the treatment of uncomplicated influenza, including in outpatients at increased risk for complications. Hideyuki Ikematsu, Ricerca Clinica, Fukuoka (H.I.), Japan, and colleagues set out to evaluate the postexposure prophylactic efficacy of baloxavir in household contacts of index patients with confirmed influenza during the 2018–2019 season in Japan.
For the purpose, they conducted a multicenter, double-blind, randomized, placebo-controlled trial. A total of 752 household contacts of 545 index patients were assigned in the ratio 1:1 to receive either a single dose of baloxavir or placebo. The primary endpoint was clinical influenza, as confirmed by reverse-transcriptase–polymerase-chain-reaction testing, over a period of 10 days. The occurrence of baloxavir-selected PA substitutions associated with reduced susceptibility was assessed.
Key findings of the study include:
- Among the index patients, 95.6% had influenza A virus infection, 73.6% were younger than 12 years of age, and 52.7% received baloxavir.
- Among the participants who could be evaluated (374 in the baloxavir group and 375 in the placebo group), the percentage in whom clinical influenza developed was significantly lower in the baloxavir group than in the placebo group (1.9% vs. 13.6%).
- Baloxavir was effective in high-risk, pediatric, and unvaccinated subgroups of participants.
- The risk of influenza infection, regardless of symptoms, was lower with baloxavir than with placebo.
- The incidence of adverse events was similar in the two groups (22.2% in the baloxavir group and 20.5% in the placebo group).
- In the baloxavir group, the viral PA substitutions I38T/M or E23K were detected in 10 (2.7%) and 5 (1.3%) participants, respectively.
- No transmission of these variants from baloxavir-treated index patients to participants in the placebo group was detected; however, several instances of transmission to participants in the baloxavir group could not be ruled out.
"Single-dose baloxavir showed significant postexposure prophylactic efficacy in preventing influenza in household contacts of patients with influenza," wrote the authors.
"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," concluded an editorialist.
The study, "Baloxavir Marboxil for Prophylaxis against Influenza in Household Contacts," is published in the New England Journal of Medicine.