[shagie]

A key point in the difference that might help explain it:

> On 13 September 1999, Gelsinger was injected with an adenoviral vector carrying a corrected gene to test the safety of the procedure

vs.

> Doctors removed his bone marrow - the part of the body that makes blood. They then genetically altered it in a lab to compensate for the defect in his DNA that caused the disease. ...

> A virus was used to infect the bone marrow with new, correct instructions.

> The corrected bone marrow was then put back into the patient.

This was a self transfusion in the lab rather than an injection of a virus. After the virus infected the bone marrow, it would then have been tested to make sure that there are no immune responses with the material and that it is safe to return to the patient.