Gilead Sciences Inc's two clinical studies of its potential coronavirus treatment remdesivir will wind down by the end of May, closing off a path of patient access to the antiviral medication, according to U.S. researchers involved in the studies. The drug was given emergency use authorization by the U.S. Food and Drug Administration on May 1, but hospitals are concerned about access. "We would like to see equitable and transparent distribution of this very precious resource," Dr. Helen Boucher, chief of infectious diseases at Tufts Medical Center in Boston, told Reuters.