Dr. Kent Brantly and Nancy Writebol, two American aid workers who recently contracted Ebola while serving in Liberia, have recovered and been released from the Atlanta-hospital isolation unit where they were treated for the virus, aid groups announced Thursday. Brantly, 33, appeared healthy and thanked health care workers, prayers and the experimental Ebola drug ZMapp for his recovery during a press conference at Emory University Hospital Thursday. 

"I cannot thank you enough for your prayers and support, but what I can tell you is that I serve a faithful God that answers prayers," he said. "God saved my life."

Writebol, a nurse, did not attend the press conferenence and declined to comment. She was released on Tuesday, according to SIM, the Christian aid group she worked for in Liberia. Both Writebol and Brantly plan to spend alone time with their families away from the media.

Brantly was reportedly brought back from the brink of death while still in Liberia using the experimental serum called ZMapp, which developers and health officials are scrambling to produce for wide distribution in West Africa. Brantly and Writebol’s aid groups, Samaritan’s Purse and SIM, secured the experimental drug for them, which the Food and Drug Administration (FDA) normally restricts for export because it hasn't been approved for use on humans.

"We don't know if it helped them... or even delayed their recovery," said Dr. Bruce Ribner, of Emory University Hospital's infectious disease division, when asked whether ZMapp helped Brantly and Writebol recover.

Brantly urged his supporters to continue to keep a spotlight on West Africa, where more than 1,350 people have been killed by the virus. Brantly said he was "glad for any attention my sickness has attracted to the epidemic in West Africa," and urged people to encourage leaders to do "everything possible" to squash Ebola in West Africa.

In a statement on Wednesday, Samaritan's Purse President Franklin Graham praised Brantly's will to fight against the disease that's killed over half of the people infected with it this year. 

"Over the past few weeks, I have marveled at Dr. Brantly’s courageous spirit as he has fought this horrible virus with the help of the highly competent and caring staff at Emory University Hospital," Graham said. "His faithfulness to God and compassion for the people of Africa have been an example to us all."

Emory University Hospital’s Serious Communicable Disease Unit is one of only four such facilities in America. It was established in collaboration with the national Centers for Disease Control, which is headquartered in Atlanta. Brantly and Writebol were flown there on Aug.2 and Aug. 5, respectively, on a private jet specially equipped to transport highly infectious patients.

Samaritan's Purse said it has around 350 staff working in Liberia, with more on the way. Doctors Without Borders, which has been on the ground in West Africa since the beginning of the outbreak, said more staff, supplies and better facilities are all needed to contain what has become the worst outbreak of Ebola in history.