A payer-perspective study from the University of Hong Kong (HKU) indicates that single-dose baloxavir is a more cost-effective outpatient treatment option for seasonal influenza than oseltamivir, despite baloxavir’s higher acquisition cost.
Hong Kong government’s Seasonal Influenza Vaccines Programme provides free vaccinations to high‐risk groups, but does not include healthy persons aged 18–50 years, meaning that some individuals are deterred from vaccination by personal cost. [https://www.chp.gov.hk/en/features/100764.html; accessed 4 May 2026] Additionally, newly emerging influenza subtypes can render existing vaccines less effective. As a result, antivirals are a necessary complementary measure for reducing the medical and economic burden of influenza. [Pharmacoeconomics 2024;42:1111-1125]
In 2023, the Hong Kong government had access to 11 million doses of antivirals, where 90 percent of the supply consisted of oseltamivir, an oral, multidose, neuraminidase inhibitor. [https://www.info.gov.hk/gia/general/202304/11/P2023041100658.htm?fontSize=1] However, resistance to oseltamivir was reported since early 2024, including among persons who had neither received prior oseltamivir treatment nor been exposed to individuals undergoing oseltamivir treatment or chemoprophylaxis. [https://www.chp.gov.hk/en/statistics/data/10/641/695/7068.html]
Baloxavir marboxil is an oral, single-dose cap‐dependent endonuclease inhibitor, which is recognized for its efficacy against strains resistant to standard antiviral agents. [Antiviral Res 2018;160:109-117] Although licensed in Hong Kong since 2019, baloxavir is not included in the Hospital Authority (HA) Drug Formulary due to its relatively high acquisition cost vs oseltamivir. [Drugs 2018;78:693-697]
“Considering [existing] resistance to oseltamivir, we expect that baloxavir would be a suitable medication to be included in the HA Drug Formulary, although baloxavir is at a price disadvantage,” wrote the researchers. [Influenza Other Respir Viruses 2026;20:e70243] Several cost‐effectiveness studies in the US and Japan have evaluated the use of baloxavir against laninamivir and oseltamivir and consistently found that baloxavir is a cost‐effective option for treating influenza in otherwise healthy (OwH) adults or high‐risk (HR) populations. [Infect Dis Ther 2024;13:2071-2087; J Infect Chemother 2021;27:296-305]
To compare the cost‐effectiveness of baloxavir and oseltamivir for influenza treatment in OwH and HR adult outpatients in Hong Kong, the researchers evaluated introducing either antiviral for outpatients with a positive rapid influenza test presenting within 48 hours of symptom onset. A decision tree was developed to model the progression of influenza and predict the associated costs and quality‐adjusted life‐years (QALYs) for baloxavir and oseltamivir, which accounted for development of treatment‐related adverse events (TRAEs), resistance to antivirals, occurrence of influenza‐related complications, hospitalization following complications, and death due to complications or other causes.
In base-case analysis, both medications demonstrated improvements in QALYs, reflecting enhanced quality of life and overall health. Baloxavir resulted in a greater QALY gain vs oseltamivir due to fewer TRAEs and complications, and a shorter duration of symptoms.
The incremental cost‐effectiveness ratio (ICER) of baloxavir vs oseltamivir was USD 13,625.98 per QALY. In the OwH group, the ICER values for baloxavir and oseltamivir were USD 145,316.3 and USD 150,267.2 per QALY, respectively, while among HR patients, these were USD 36,162.19 and USD 86,684.27 per QALY.
“Both treatments are cost‐effective at the USD 152,667 willingness‐to‐pay threshold. However, baloxavir demonstrates greater cost‐effectiveness than oseltamivir under the base‐case assumptions, particularly in HR patients,” wrote the researchers. “Therefore, we recommend integrating baloxavir into the HA Drug Formulary in Hong Kong [in order to] enhance healthcare resource allocation and improve patient outcomes.”