The U.S. physician who contracted ebola “seems to be improving,” according to the head of the Centers for Disease Control and Prevention. Kent Brantley was flown from Liberia to the U.S. on Saturday and is currently being treated in a special isolation unit at Emory University Hospital in Atlanta. "We're hoping he'll continue to improve. But Ebola is such a scary disease because it's so deadly. I can't predict the future for individual patients," said CDC Director Tom Frieden. Nancy Writebol, another American in Liberia who contracted the virus, is set to arrive in the U.S. in a few days. Frieden also assuaged concerns about a possible ebola outbreak in the U.S. “We say in medicine never say never. But we know how to stop it here,” he said, expressing more concern about its spread in Africa. So far, the virus has killed 729 people in West African nations and infected more than 1,300.