According to He Xiangling, director of pediatric hematology and oncology at Hunan Provincial People's Hospital, the disease the boy suffers is a primary immunodeficiency with impaired phagocytic function. It's characterized by repeated fungal and bacterial infections, causing decreased immunity. Patients typically take antibiotics for long-term treatment.

Data shows the incidence of the life-threatening disease is one in every 200,000 to 250,000 people.

The director said the only cure is to perform a hematopoietic stem cell transplant.

Fortunately, genetic matching went well for the boy's 14-year-old sister. During the collection of hematopoietic stem cells, the sister had a vasospasm due to thin blood vessels. Despite the pain, the girl held back her tears for 6 hours, and finally completed the extraction of the cells that saved her brother's life.

The boy had a full recovery by Jan 6, around 25 days after the transplant.

He Xiangling stressed whole immune reconstruction usually takes about six months, and regular examinations and medication adjustments are required after the boy is discharged from hospital. Without these checks, a serious infection could seriously threaten the child's life.

Wu Yunru contributed to this story.