Ebola patient Amber Vinson arrived by ambulance at Emory University Hospital on Oct. 15. Now healthy, Vinson was discharged from the hospital Tuesday. Kevin C. Cox/Getty Images hide caption

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Dallas nurse Nina Pham speaks at a press conference after she was confirmed free of Ebola and released from a National Institutes of Health facility on Friday. Alex Wong/Getty Images hide caption

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At a CDC training session for clinicians headed to West Africa, a medical worker practices sanitizing hands after drawing blood from a mannequin portraying an Ebola patient. Brynn Anderson/AP hide caption

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When a high-risk patient is evacuated, strict precautions are followed. Above, aid workers and doctors in protective gear transfer Manuel Garcia Viejo, a Spanish priest diagnosed with Ebola, to a waiting ambulance at a Madrid airport. Spanish Defense Ministry/AP hide caption

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The entrance to the emergency room at Texas Health Presbyterian Hospital Dallas, where Thomas Eric Duncan was treated before he died from Ebola a week ago. Two health care workers who treated Duncan have tested positive for the disease. LM Otero/AP hide caption

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A plane arrives at New York's John F. Kennedy International Airport. Since Ebola screenings began Saturday, none of the 91 passengers identified as having an increased risk of an Ebola infection was found to be sick, the CDC says. Spencer Platt/Getty Images hide caption

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Passengers from three West African countries will face screening for Ebola symptoms when they arrive at John F. Kennedy International Airport in New York. Travelers are seen here at a JFK checkpoint earlier this week. Four other airports will begin screening next week. JUSTIN LANE/EPA /LANDOV hide caption

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Dallas County Judge Clay Jenkins, right, escorts people who were at the apartment unit where Thomas Eric Duncan, a Liberian citizen diagnosed with the Ebola virus, had been staying. Jenkins used his car to drive the people to a new place to stay in Dallas. JIM YOUNG/Reuters /Landov hide caption

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