Avigan May Improve Hantavirus Survival Rates, Animal Studies Suggest

Japan Supplies Antiviral Drug to U.K. In Response to Hantavirus Outbreak

LONDON — May 18, 2026 — In a move underscoring deepening U.K.-Japan pharmaceutical cooperation, Japan has supplied a limited quantity of the antiviral drug Avigan (favipiravir) to the United Kingdom, where preliminary data from animal studies suggests the medication may improve survival rates among patients infected with hantavirus. The transfer follows a request from British health authorities amid a localized outbreak in northern England, where cases have risen in recent weeks.

While there is no established cure for hantavirus—a potentially fatal respiratory illness transmitted by rodents—Japanese researchers have reported promising results in animal trials, with Avigan demonstrating efficacy in reducing mortality rates. The drug, developed by Fujifilm Toyama Chemical, has been approved in Japan for influenza but has not undergone large-scale human trials for hantavirus treatment.

A Diplomatic and Medical Partnership

The supply of Avigan marks the latest chapter in U.K.-Japan scientific collaboration, building on existing agreements to share medical countermeasures during public health emergencies. A spokesperson for the U.K. Department of Health and Social Care confirmed that the drug would be distributed to affected regions under emergency-use protocols, with close monitoring by the UK Health Security Agency (UKHSA).

Japan’s Ministry of Health, Labour and Welfare (MHLW) stated in a briefing that the decision to provide Avigan was made in consultation with British officials, citing "the gravity of the situation and the potential benefit to patients." The move also reflects Japan’s broader strategy of leveraging its pharmaceutical expertise to strengthen global health security alliances, particularly with key partners like the U.K.

Limited Evidence, Urgent Need

Hantavirus infections in the U.K. Have been rare but severe, with recent cases concentrated in rural areas where rodent populations are high. The UKHSA has not yet confirmed whether Avigan will be administered to confirmed patients, pending further ethical review and clinical assessment. However, the agency’s director of emergency response, Dr. Emma Davies, noted in a statement that "every potential avenue is being explored to improve outcomes for those affected."

The World Health Organization (WHO) has previously classified hantavirus as a priority pathogen due to its high fatality rate and lack of effective treatments. While Avigan’s mechanism—disrupting viral RNA synthesis—has shown promise in lab settings, its real-world efficacy against hantavirus remains unproven in humans. Japanese health officials emphasized that the supply was not a blanket endorsement but a goodwill gesture to support urgent research.

Broader Implications for Global Health Security

The Avigan transfer comes as both nations navigate post-pandemic health diplomacy, with the U.K. And Japan collaborating on vaccine development, antimicrobial resistance, and zoonotic disease preparedness. The move may also accelerate discussions on international drug-sharing protocols, particularly for orphan diseases with limited treatment options.

For now, British health authorities are urging the public to reduce rodent exposure—the primary prevention measure—while scientists work to determine whether Avigan can bridge the gap until a dedicated hantavirus therapy is developed.

For Public Health Guidance:

• UK Health Security Agency (UKHSA): www.gov.uk/ukhsa
• Japanese Ministry of Health, Labour and Welfare (MHLW): www.mhlw.go.jp
• Hantavirus Prevention Tips: WHO Hantavirus Fact Sheet