evidence: The results suggested a survival benefit, with a mortality rate of 8% for the group receiving remdesivir versus 11.6% for the placebo group, according to a statement from the National Institutes of Health released later Wednesday. [...] Gilead also released preliminary results from its own study, showing at least 50% of the patients treated with a five-day dosage of remdesivir improved. The clinical trial involved 397 patients with severe cases of Covid-19. The severe study is "single-arm," meaning it did not evaluate the drug against a control group of patients who didn't receive the drug. [...] Remdesivir has shown some promise in treating SARS and MERS, which are also caused by coronaviruses. Some health authorities in the U.S., China and other parts of the world have been using remdesivir, which was tested as a possible treatment for the Ebola outbreak, in hopes that the drug can reduce the duration of Covid-19 in patients.