March 18th we learned that China is using this successfully
Japanese flu drug 'clearly effective' in treating coronavirus, says China
https://www.theguardian.com/world/2020/mar/18/japanese-flu-drug-clearly-effective-in-treating-coronavirus-says-china
Medical authorities in China have said a drug used in Japan to treat new strains of influenza appeared to be effective in coronavirus patients, Japanese media said on Wednesday.
Zhang Xinmin, an official at China’s science and technology ministry, said favipiravir, developed by a subsidiary of Fujifilm, had produced encouraging outcomes in clinical trials in Wuhan and Shenzhen involving 340 patients.
“It has a high degree of safety and is clearly effective in treatment,” Zhang told reporters on Tuesday.
Patients who were given the medicine in Shenzhen turned negative for the virus after a median of four days after becoming positive, compared with a median of 11 days for those who were not treated with the drug, public broadcaster NHK said.
In addition, X-rays confirmed improvements in lung condition in about 91% of the patients who were treated with favipiravir, compared to 62% or those without the drug.