This link states Moderna's position on the third shot.
Moderna Asks FDA To Authorize A Booster Shot Of Its COVID-19 Vaccine. : Coronavirus Updates : NPR
All the rest of the arm waving is either special interest motivated,
or the inefficient process of approvals (on top of approvals).
Moderna was and still is under the "emergency approval to distribute" awaiting all the rubber stamps and quid quo pros to take place.
I don't see Moderna changing anything after approval that they are doing or not doing today.
We got our third dose yesterday at Publix. They require an appointment that can only be made on line. Very user friendly site (Google Publix third shot). Our appointments were 1:00 and 1:15 PM and on our way by 1:20 PM.
Side effects? None!