Hantavirus Outbreak: Britain Turns To Experimental Japanese Drug Favipiravir — And It Has A COVID Connection

As concerns grow over the recent hantavirus outbreak linked to the Antarctic cruise ship MV Hondius, United Kingdom authorities have reportedly secured emergency supplies of the experimental antiviral drug Favipiravir from Japan.

The drug may not be widely known to the public, but it gained global attention during the early stages of the COVID-19 pandemic, when several countries explored it as a possible treatment option against the coronavirus.

What Is Favipiravir?

Favipiravir was originally developed by Toyama Chemical, now part of Fujifilm, and marketed under the brand name Avigan.

The drug was approved in Japan in 2014 for emergency use against new and emerging influenza strains. Unlike antibiotics, which target bacteria, Favipiravir works by interfering with the RNA polymerase enzyme that many RNA viruses rely on to reproduce. Because of this mechanism, scientists classify it as a broad-spectrum antiviral.

Researchers have studied the drug against several RNA viruses over the years, including influenza viruses, Ebola, and hantaviruses.

Its COVID-19 Connection

During the early phase of the COVID-19 pandemic, countries including India, Russia and Japan experimented with Favipiravir as a treatment for mild and moderate COVID-19 cases.

The medication attracted attention largely because it was available in pill form, making it easier to administer outside hospitals compared to intravenous antivirals.

Initial small-scale studies suggested it might shorten recovery time or reduce viral replication. However, larger reviews and later studies produced inconsistent findings, with no strong evidence that the drug significantly reduced deaths or prevented severe disease progression in COVID-19 patients.

Although it never became a breakthrough COVID treatment, the drug remained on the radar of governments and health agencies for emergency outbreak situations.

Why Is Britain Importing It Now?

The current concern centres around the Andes hantavirus infection, a rare strain of hantavirus known for its unusual ability to spread between humans under certain circumstances.

According to reports, the UK Health Security Agency moved quickly to secure supplies of Favipiravir after fears emerged that infected individuals linked to the Antarctic cruise outbreak could develop severe illness.

At present, there is no officially approved antiviral treatment for hantavirus pulmonary syndrome, a severe respiratory disease associated with certain hantavirus strains. The condition can become life-threatening rapidly, with mortality rates for Andes virus infections estimated at around 35–40 percent in serious cases.

Animal studies and limited human reports have hinted that Favipiravir may offer some benefit against hantaviruses, though evidence remains limited and inconclusive.

For now, treatment for severe hantavirus infection still relies mainly on supportive care, including oxygen therapy, intensive monitoring, fluids and respiratory support.

Risks And Precautions

Despite the renewed interest, Favipiravir is not without risks. Studies have linked the drug to birth defects in animals, meaning it is generally avoided during pregnancy. Doctors must also monitor patients for potential side effects such as liver complications, elevated uric acid levels linked to gout, and gastrointestinal issues.

The drug is reportedly being considered under compassionate-use or experimental protocols rather than as a fully approved treatment.

A Post-Pandemic Reality

The rapid movement of antiviral stockpiles between countries also reflects how outbreak response strategies have changed since the COVID-19 pandemic. Governments are now more willing to deploy experimental treatments quickly while health agencies coordinate internationally during emerging health threats.

Health authorities, including the World Health Organization, continue to stress that the broader public risk from the current hantavirus situation remains very low, and experts say the outbreak does not resemble the global conditions that fueled COVID-19 transmission.

Still, the return of Favipiravir to headlines serves as a reminder of how quickly old outbreak tools can re-emerge when new health threats appear unexpectedly.