Moderately ill COVID-19 patients saw their condition improve after a 5-day course of Gilead Sciences Inc’s (GILD.O) remdesivir, but the drug did not significantly shorten hospital stays and a 10-day course did not show a benefit, according to new data. The drug, which was shown in a trial of severely ill COVID-19 patients to shorten their hospital recovery time, has been at the forefront of the battle against the pandemic. The 600-patient analysis, published on Friday by the Journal of the American Medical Association, found that moderately ill patients treated with the antiviral drug for up to 5 days had significantly higher odds of improvement in certain areas, such as whether or not they needed supplemental oxygen, compared to patients given standard treatment. Researchers said the clinical importance of the benefit for those patients was uncertain, however. Remdesivir is currently sold under an emergency use authorization from the U.S. Food and Drug Administration for treating patients hospitalized with severe COVID-19, the disease caused by the new coronavirus. Gilead earlier this month filed an application seeking full FDA approval of the drug. Differing trial results for remdesivir raise “the question of whether the discrepancies are artifacts of study design choices, including patient populations, or whether the drug is less efficacious than hoped,” according to a JAMA editorial accompanying the study. The new study in moderately ill COVID-19 patients showed that 11 days after starting treatment, 65% of the 10-day remdesivir patients, 70% of the 5-day patients and 60% of the standard care patients had left the hospital. Side effects seen more frequently in the remdesivir groups included nausea, low blood potassium levels, and headache. The JAMA editorial said important questions remain regarding the efficacy of remdesivir, including which patients are most likely to benefit from the drug, the optimal duration of therapy, the drug’s impact on clinical outcomes, and its relative effect if combined with generic steroid treatments. Shares of Gilead were up 18 cents at $66.24 on the Nasdaq exchange.