Frieden dismissed suggestions that people traveling from West Africa should not be allowed into the U.S.
"The fact is that if we tried to seal the border, it would not work because people are allowed to travel," he told ABC. "It would backfire because it would make it harder to stop the outbreak."
Duncan arrived in Dallas on Sept. 20 and fell ill a few days later. An emergency room sent Duncan home last week, even though he told a nurse he had been in West Africa.
In a statement issued late Thursday, Texas Health Presbyterian Hospital said it followed communicable disease protocols by asking Duncan if he had come into contact with anyone who was ill. He replied that he had not.
A flaw in the electronic health records systems led to separate physician and nursing workflows, meaning the travel history documented by nurses was not passed onto physicians, hospital spokesman Wendell Watson said. He said the system has been corrected.
Duncan’s symptoms included a 100.1 F temperature, abdominal pain, a headache and decreased urination, the hospital said. He said he had no nausea, vomiting or diarrhea. Based on that, the hospital decided to release him.
He returned two days later and has been kept in isolation since Sunday. Duncan was listed Thursday in serious but stable condition.