Earlier quoted context omitted.
In the Netherlands the Moderna vaccine is not used for younger groups. I think the cutoff is 40. Anyone over 12 can get vaccinated and get a booster, but it will be the Pfizer vaccine.
Note that Moderna's booster volume of antigen was reduced by 50% compared to the original vaccine, while Pfizer's booster volume was unchanged from the original vaccine, https://www.modernatx.com/covid19vaccine-eua/providers/dosin...
Moderna did reduce its dose for the booster, but its original dose was also 3x that of Pfizer.