Because COVID-19 didn’t exist then, and this tech was originally supposed to be used for ‘gene therapy’ - which it failed at. Genetic changes were not able to be effected by this means. However, the tech had some success in treating other diseases and prior to COVID-19, it produced the first working and approved Ebola vaccine.
I understand COVID-19 didn’t exist then. I stated the coronavirus which has been around forever. I have read multiple articles stating for decades a vaccine for the coronavirus was a pipedream. I was just curious what change occurred with COVID-19 that allowed the decades old tech from J&J to work now and not then.