Gilead Sciences Inc.’s experimental drug for patients with severe Covid-19 infections showed promise in an early analysis, raising tentative hope that the first treatment for the novel virus may be on the horizon. The report published in the New England Journal of Medicine tracked 53 people in the U.S., Europe and Canada who needed respiratory support, with about half receiving mechanical ventilation and four on a heart-lung by-pass machine. Eight additional patients were left out of the analysis: one due to a dosing error and seven because no information was available on how they fared. Over 18 days, 68% of the patients improved, with 17 of the 30 patients on mechanical ventilation being able to get off the breathing device. Almost half of the patients studied were ultimately discharged, while 13% died. Mortality was highest among those who were on a ventilator, with 18% of them dying.