Nancy and David Writebol are headed back to Liberia this weekend, eight months after she became the second American infected with the Ebola virus.
Nancy Writebol, a medical missionary, made headlines around the world when she was evacuated by air to Emory University Hospital in Atlanta, where she and her colleague Dr. Kent Brantly recovered from the highly deadly virus.
"Liberia is still very much a part of our lives and our hearts," Nancy Writebol said.
Like all survivors, Nancy Writebol is considered immune to the virus — although it's not something anyone would ever deliberately test.
And David Writebol may also be immune. He's one of the volunteers testing an experimental vaccine against Ebola.
Both Nancy and David were recently at Emory to help doctors study their immunity. Nancy is donating plasma that might be used to help treat other Ebola patients.
"I am just very thankful to be able to do that and thrilled to be able to help others who may contract Ebola," she told NBC News as she sat hooked up to a plasmapheresis machine that was taking out her blood, separating the red and white blood cells from the golden plasma, and returning the cells to her body.
"I am very thankful to give back and to help others who may need that and also just for the furtherance of research."
Writebol had already donated plasma to be infused into other patients. Now, Dr. Anne Winkler, an Emory pathologist, is leading a study to examine the plasma and test it in patients to see just whether it can help Ebola patients recover.
The plasma contains antibodies that should recognize and neutralize Ebola.
"The plan is that the bank would supply any plasma throughout the United States for any patient," Winkler said.
"They would become great donors if they had neutralizing antibodies," she added. "We know that not everyone with Ebola actually develops neutralizing antibodies. So, part of the study is to actually characterize the antibody profiles in survivors of Ebola virus disease."
A second team at Emory is studying David Writebol's blood to see if the experimental vaccine he was given has stimulated a similar immune response. The same vaccine is now being tested in people in Liberia and Sierra Leone who are at risk of infection.
"It's a privilege to be a part of that trial," David Writebol said. "The research is ramping up to test the effectiveness of the vaccine, and we don't know how all the results of that are going to be, but it's good to know that we can again continue to serve and be a help."
The Ebola vaccines use other, harmless viruses to carry tiny pieces of the Ebola vaccine into the body. In David's case, it's a common cold virus called an adenovirus that usually infects chimpanzees but not people. He said he felt a slight reaction to the vaccine.
"It was just pretty mild really — just a little bit of achiness," he said. "I didn't spike a fever or anything and it lasted for about 12 hours and after that, (I felt) pretty normal."
They leave for Liberia Sunday.
"We are excited to be able to go back, and we just want to see how things are and visit with our Liberian friends and understand a little bit more about their struggles," David Writebol said.
Nancy became infected in July while working at an Ebola clinic run by her employer, Serving in Mission (SIM), outside Monrovia.
She spent an uncomfortable few days in the couple's home, being treated for Ebola. David was not allowed to approach her and sat outside their bedroom window. "Those were very stressful, tense moments," he said.
And they have mixed emotions about returning to Liberia, says David. Ebola's infected nearly 24,000 people in West Africa and killed more than 9,600. In Liberia alone, more than 9,000 have been infected and 3,900 have died.
"We don't know psychologically how exactly we are going to feel," David said. "I know sometimes when we think about it, there is a bit of emotion in that because those were very stressful days and revisiting that will, I'm sure, have a bit of an impact on that."
But they'll be keen to see friends and colleagues. "They have survived Ebola and we have also survived Ebola and so we have a lot in common that we can, that we can share together and help each other," David added.
Liberia only has one known new case of Ebola now, but health officials say the epidemic is not over. They worry that people may relax precautions, such as careful handwashing and careful burial of bodies.
And Nancy does not intend to test the theory that she's immune. "I think that there is still a respectful fear of Ebola no matter if you've had it or if you have not," she said.
"And although I am considered immune, I still think there is all the reason to continue to be cautious and to just really encourage our Liberian brothers and sisters to remain cautious," she added.