There is hope that the experimental drug remdesivir could cure patients of coronavirus after a 79-year-old Italian man who had tested positive was given the all-clear after treatment.
The broad-spectrum antiviral was developed by US drug firm Gilead for Ebola and was used to treat Scottish nurse Pauline Cafferkey when she suffered a relapse 18 months after being cleared of the disease which she contracted while volunteering in Sierra Leone.
Currently, remdesivir is being tested in five Covid-19 clinical trials including by the US National Institutes of Health (NIH) on 13 patients hospitalised after contracting coronavirus on board the Diamond Princess cruise ship in Japan.
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The first person to test positive with the virus in the US was also treated with drugs and has since fully recovered.
A case report in the New England Journal of Medicine said the man began to feel better within a day of being treated with intravenous remdesivir.
On Tuesday evening, the President of Italy's Liguria region Giovanni Toti said the area had seen "the first real case of coronavirus cured", a 79-year-old man who was treated with remdesivir. He is due to return to his home in Lombardy soon.
Bruce Aylward, of the World Health Organisation, said last month: "There's only one drug right now that we think may have real efficacy. And that's remdesivir."
Drug maker Gilead, which distributed the drug on a compassionate use basis to several hundred patients globally, expects to start its own late-stage trials this month.
Remdesivir has so far been proven to inhibit the related virus Mers-CoV - the cause of Middle East Respiratory Syndrome (Mers) in animal models. However, a study out last week on three US patients showed mixed results.
There are currently no approved therapies for coronavirus, but many countries have been repurposing anti-virals in the hope they might work against the infection.
Thailand claims to have cured some patients with a combination of the dual HIV antivirals ritonavir-lopinavir and Tamiflu. China has also approved the antiviral favilavir for use in coronavirus.
Additionally, the anti-malarial chloroquine has shown efficacy in some early lab trials.
The first clinical trial for a vaccine has begun in the US after skipping animal trials.