The National Institutes of Health said it will conduct a randomized, controlled clinical trial testing a combination of Gilead Sciences Inc.'s /zigman2/quotes/210293917/composite GILD +0.98% remdesivir with Merck KGaA's /zigman2/quotes/200605022/delayed DE:MRK +0.37% interferon beta-1a as a treatment for COVID-19 patients. The study plans to enroll 1,000 people who have been hospitalized because of a COVID-19 infection. The federal agency said it expects to have preliminary results in the fall. Since the Food and Drug Administration granted an emergency use authorization to remdesivir in May, several clinical trials have been initiated that aim to pair the investigational therapy with other drugs to see if the combination can better treat severely ill COVID-19 patients. This includes another NIH trial pairing remdesivir with Eli Lilly & Co. /zigman2/quotes/200106384/composite LLY +0.98% and Incyte Corp. /zigman2/quotes/204510994/composite INCY +0.64% 's Olumiant. Roche Holding AG /zigman2/quotes/206324342/delayed CH:ROG +0.92% has also said it will test its rheumatoid arthritis drug in combination with remdesivir.