Born nearly two months early in July, Addison then suffered an infection that brought her to the Neonatal Intensive Care Unit at Medical College of Georgia, where surgery removed a good portion of her small and large intestines, leaving her with a limited capacity to absorb nutrition.
She recently came off a feeding tube and ravenously attacks the small bottle her mother gives her.
"She's a little hungry," Andrea Poppell said as the bottle's contents dwindled.
Addison has fought off one virus; her mother is hoping a shot will help protect her against a common one that could cause serious problems for preemies like her.
Called respiratory syncytial virus, it is common in the winter months, particularly in infants.
"Almost 100 percent of kids by age 2 are going to have RSV," said Jatinder Bhatia, the chief of the section of neonatology at MCG.
"You and me, we may sniffle and that's it. In a child, they may cough a little bit and that's it."
But preemies and babies with other lung problems can develop life-threatening infections that put them in the hospital and sometimes on heart-lung bypass.
A vaccine against RSV was pulled several years ago, but then came a powerful monoclonal antibody called Synagis, which targets a specific protein in the virus.
That drug has reduced hospitalizations from RSV by 50 percent.
The problem is, it must be given in a series of monthly shots, and the immunity does not begin until after the second shot.
"So there's that vulnerability period," Bhatia said.
MCG is testing a new monoclonal antibody called Numax that proved to be 18 times more potent in lab tests and 50-100 times more effective against the virus in rats.
MCG is enrolling premature infants to get either Synagis or Numax, with the hope that Numax proves more powerful in humans.
"Because if there's a much better one, then it's going to do a much better job than Synagis does," Bhatia said.
"Your vulnerability goes away as soon as you get the first shot, that's my hope."
Having already overcome so much in her first 4 months of life, Poppell is hoping to at least shield her daughter from RSV by getting Addison the Synagis shots before they return to Thomasville, Ga.
"She can only fight so many things," Poppell said.
"If they have to start treating her for something like that, it just makes it that much worse."