A simple cold could have been fatal for Cora Oakley.
Born in Morristown, New Jersey, Cora had virtually no immune system due to severe combined immunodeficiency (SCID), a rare genetic disease that deprives the body of crucial white blood cells.
Commonly known as “bubble boy disease,” it was made famous by the 1976 film, “The Boy in the Plastic Bubble.” Although no longer requiring plastic bubbles, most infants with SCID wouldn’t survive their first year without treatment.
“It seems you have a perfectly healthy child who’s happy and reaching milestones,” said Chelsea Ferrier, Cora’s mother. “But she’s actually sick. She can’t do anything. She can’t go outside.”
The standard SCID treatment is a bone-marrow transplant, ideally from a perfectly matched sibling. Cora was Ferrier’s first child, her “miracle” after years of miscarriages, so she had no sibling donor.
In 2017, a new treatment was in clinical trials—a gene therapy aimed at repairing Cora’s stem cells rather than replacing them. Annually, up to 100 U.S. babies are born with SCID, caused by over 20 genetic defects. Cora had ADA-SCID, among the few types targeted by gene therapy to restore immune function.
“I would have sold my organs to get into that trial,” Ferrier said. Cora secured the last slot.
For decades, a SCID baby’s survival hinged on swift diagnosis and a bone-marrow transplant—a procedure with severe side effects.
Recent research tracking 62 ADA-SCID babies who received gene therapy showed that nearly eight years later, all were alive. In about 95% of cases, including Cora, the therapy fully restored their immune systems.
Gene therapies are now being tested for four of SCID’s 20 subtypes, offering hope to treat two-thirds of affected infants.
“This was a fairy tale 20 years ago,” said Frank Staal, a Netherlands-based stem cell researcher uninvolved in the study. “Now it’s a reality.”
From Transplants to Gene Therapy
Bone-marrow transplants have long been lifesaving for SCID infants but come with the risk of severe side effects.
In the U.S., all newborns are screened for SCID. Within months of diagnosis, affected babies undergo chemotherapy followed by a transplant. This process destroys diseased marrow, allowing donor stem cells to thrive, explained Dr. Morton Cowan, a pediatric immunologist.
Within six to 12 months, new marrow produces white blood cells, rebuilding the immune system. However, recovery can be precarious: New cells may reject the body, a condition known as graft-vs-host disease. Immunosuppressant drugs are often necessary, leaving babies vulnerable to infections.
“It’s a paradox: Suppressing immunity while wanting it to grow,” said Dr. Donald Kohn, who led the new study.
Long-term side effects, like stunted growth and organ damage, can follow chemotherapy.
Researchers have turned to gene therapy for safer alternatives, said Dr. Susan Prockop. Since SCID stems from a faulty gene, scientists collect and modify babies’ stem cells in the lab, using a disabled form of HIV to deliver a healthy gene. The corrected cells are reintroduced to grow healthy immune cells.
With gene therapy, only a low chemotherapy dose is needed, and since it uses the infant’s own cells, rejection risk is minimal. Recovery is quicker with fewer side effects.
Hailey Barlow, from Utah, saw this change in her family. Her first daughter, Jaylee, had a bone-marrow transplant in 2010; her second, Hazel, received gene therapy in 2023.
Jaylee spent months in the hospital fighting graft-vs-host disease, while Hazel recovered swiftly, returning home in a month.
“You couldn’t tell Hazel had been sick,” Barlow said, noting the stark contrast between treatments.
Living With SCID
SCID remains a lonely disease, as families must protect infants from germs while their immune systems rebuild.
“SCID parents are constantly anxious about infections,” said Kohn.
Nicole Haggard, from California, knows this fear too well. SCID claimed most boys in her family by three months old.
Gene therapy gave her son, Dezar, a chance at normalcy, but the fear lingered. Visitors changed clothes at the door, parks were off-limits, and decisions were stressful.
As Dezar’s immune system improved, their world expanded. But even now, a fever causes anxiety. “We always fear it’s something bigger,” Haggard said.
Doctors are hopeful about gene therapy but note its novelty. Bone-marrow transplants have decades of data; gene therapy, only years, said Dr. Richard O’Reilly. The long-term viability of repaired immune systems and risks remain uncertain.
Access to gene therapy is another concern, with costs in the millions per patient and no pharmaceutical company ready to market it. Currently, it’s available only in clinical trials, supported by nonprofits and agencies like the California Institute for Regenerative Medicine. But trials are not indefinite.
“It’s rare to completely cure disorders so infants never show symptoms,” Prockop said, “but it’s meaningless if families can’t access it.”
For now, Cora’s life is delightfully ordinary, Ferrier said. At eight, she’s fearless, eager to help homeless kittens, and stops to learn the name of every dog she sees.
“I can’t imagine what life would be like if Cora hadn’t had this chance,” Ferrier said.
This article originally appeared in The New York Times.
Chelsea Ferrier with her daughter Cora Oakley, who was born with severe combined immunodeficiency, in Morristown, New Jersey, on November 25, 2025. — Lindsay Perryman/The New York Times
