On 23 March 2025, the day before the procedure, the family settled into a shared room inside a crowded pediatric ward. When the other girl in the room broke into tears, Mei handed her one of her favorite stuffed animals: a blue bird. The next day Mei put on a brave face as she was taken to the procedure room. Yu’s handpicked doctor inserted a needle between two vertebrae on her lower back and withdrew just over a teaspoon of spinal fluid to create space for the drug. Then, he swapped syringes and gently pressed down on the plunger, filling her spinal canal with viruses.