A global study led by HKUMed reveals that a single dose of baloxavir can significantly cut the transmission of influenza within households, potentially changing the future of flu control.
Key Points at a Glance
- A single oral dose of baloxavir reduced household influenza transmission by 32%.
- Baloxavir accelerated viral clearance compared to placebo.
- No significant new safety concerns were identified during the study.
- Results highlight baloxavir’s potential as a complement to vaccination strategies.
- The findings were published in The New England Journal of Medicine.
Influenza sweeps across the globe every year, sickening millions and overwhelming healthcare systems. While vaccination remains the frontline defense, scientists have long searched for additional strategies to halt the spread of this persistent virus. Now, a groundbreaking international study led by the LKS Faculty of Medicine at the University of Hong Kong (HKUMed) offers compelling new hope: a simple oral medication could serve as a powerful weapon in containing influenza outbreaks.
Published in The New England Journal of Medicine, the CENTERSTONE trial is the first robust clinical study to demonstrate that an antiviral treatment can significantly reduce influenza transmission within households — the primary hotbeds of viral spread. The global research effort enrolled 1,457 influenza-positive individuals (termed “index patients”) and 2,681 of their household contacts across 15 countries, spanning the years 2019 to 2024.
Participants aged between 5 and 64 years received either baloxavir marboxil — a single-dose antiviral medication — or a placebo, administered within 48 hours of the onset of flu symptoms. Researchers then monitored the spread of the virus among household contacts over the next five days.
The results were striking. Households where the index patient received baloxavir experienced a 32% reduction in the odds of untreated household members contracting the virus compared to those receiving a placebo. Symptomatic transmission rates were also lower among the baloxavir group (5.8%) than the placebo group (7.6%), though the difference did not reach statistical significance.
Further bolstering baloxavir’s credentials, the treatment led to a faster reduction in viral titers — the quantity of virus present in the body — showcasing a mean reduction of 2.22 log₁₀ TCID₅₀/mL by day three, compared to 1.85 log₁₀ TCID₅₀/mL in the placebo group. Notably, while drug-resistant viral strains emerged in 7.2% of baloxavir-treated patients, these strains were not transmitted to household contacts, alleviating fears of promoting resistant infections.
Perhaps most reassuringly, baloxavir demonstrated a strong safety profile. Adverse events occurred in only 4.6% of baloxavir recipients, compared to 7.0% among those given a placebo.
Professor Benjamin Cowling, co-author of the study and Chair Professor of Epidemiology at HKUMed, emphasized the broader significance of the findings: “These results highlight baloxavir’s potential not only to treat influenza but also to reduce its spread within communities. This dual effect could transform how we manage seasonal influenza and prepare for future pandemics.”
Indeed, the implications stretch far beyond seasonal flu. In pandemic scenarios — where vaccine supply may lag behind viral spread — antiviral drugs like baloxavir could offer a vital line of early defense. Moreover, for populations with low vaccine uptake, the availability of a treatment that also reduces transmission could dramatically alter public health strategies.
While vaccination remains crucial, the CENTERSTONE trial points to an exciting complementary tool. With a simple pill, it might soon be possible not only to recover faster from influenza but to help protect family members and communities at the same time.
