"Moderna had hundreds of vials of its vaccine shipped to the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland by February 24. Everything that has happened since — 1.4 million deaths worldwide, crippling lockdowns — has gone on while we were waiting for that vaccine to be tested, approved, and distributed."
"Moderna’s testing was slowed for a critical juncture by demands to include more racial minorities in the trials."
I guess the demands came from the FDA. Regardless, clinical trials were yet to be done, and they take a long time. Reference: Coronavirus – clinical trials #2
Update Dec 7: We Had the Vaccine the Whole Time