Writebol was released Tuesday and Brantly was discharged Thursday.
“Today is a miraculous day,” Brantly said during the news conference. “I am thrilled to be alive, to be well and to be reunited with my family.”
Brantly said he moved with his family to Liberia last October to start a two-year medical aid mission for the Christian aid organization Samaritan's Purse.
He encountered his first Ebola patient in June and was diagnosed with the disease on July 23 after experiencing symptoms, which quickly led to his becoming bedridden for nine days at a Liberian hospital. “As a medical missionary, I never imagined myself in this position,” Brantly said.
Both Brantly and Writebol received the experimental Ebola treatment drug ZMapp before returning to the U.S. The medication had not been tested on humans and was not approved by the Food and Drug Administration.
Ribner said he did not know what role, if any, the drug played in the recovery of Brantly and Writebol.
“We do not know whether it helped them, whether it made a difference, or even theoretically, if it delayed their recovery,” Ribner said.
Ribner said there was no evidence that either patient was still carrying the disease. There is no vaccine or approved treatment for Ebola, which has a death rate as high as 90%.
The current outbreak is the worst ever recorded. The latest figures from the World Health Organization as of Aug. 18 tally the total number of cases since the outbreak began in March at more than 2,400 cases, with more than 1,300 deaths across Liberia, Guinea, Sierra Leone and Nigeria.
Follow Steven Ross Johnson on Twitter: @MHsjohnson