Randomized trials of the broad-spectrum antiviral favipiravir, marketed as an anti-influenza treatment by Fujifilm Holdings Corp., have shown "obvious efficacy" against COVID-19, according to Zhang Xinmin, head of the China National Center for Biotechnology Development. Zhang's comments were reported by Xinhua News Agency, China's official state-run press agency.

Remarks about the drug's apparent promise, made during a press conference hosted by Chinese government officials on March 17, drove Fujifilm shares (TYO:4901) up 15.4% to ¥5,230 (US$48.55) by the close of March 18 trading in Tokyo. It was the second time the stock rose in anticipation of the antiviral's potential application for treatment of COVID-19.

In one trial, testing favipiravir with interferon in Shenzhen, results showed that patients treated with the combination had significantly reduced the duration of symptoms, as measured by viral load chest imaging, vs. a control group. In another study, clinical recovery rates were higher for COVID-19 patients treated with favipiravir vs. those in a control group.

According to Xinhua, Zhang said that favipiravir has been recommended to medical treatment teams and should be included in treatment plans for COVID-19 as soon as possible. Furthermore, he said, a Chinese pharmaceutical company – possibly Zhejiang Hisun Pharmaceutical Co. Ltd., which bought exclusive rights to favipiravir from Fujifilm's Toyama Chemical Co. Ltd. – has been approved by the National Medical Products Administration to mass-produce the drug and ensure stable supply.

Fujifilm representative Christine Jackman told BioWorld the company "is not in a position to talk about the use of favipiravir for coronavirus patients in China or Japan," but that, as a viral RNA polymerase inhibitor with a mechanism of action that inhibits viral gene replication within infected cells, the medicine "is expected to have an antiviral effect on avian influenza A (H5N1 and H7N9) and other viruses."

Avigan obtained its first approval in Japan in March 2014, ahead of other countries, "after the authorities considered the current situation of influenza and recognized the significance" of making it available to "establish preparedness against the possible outbreak of novel or re-emerging influenza virus infections, to which neuraminidase inhibitors or other anti-influenza drugs could be ineffective or not sufficiently effective," she said.

Both Hisun and Sihuan Pharmaceutical Holdings Group Ltd. have been testing the medicine, part of a group of six trials of the drug, originally developed for influenza and also tested against Ebola virus disease.