The FDA emergency-authorized Moderna and J&J booster shots today, also adding that all three vaccines could be "mixed-and-matched" - meaning if you received the initial dose or doses of one, the third shot could be of another vaccine.
The next step is the CDC will vote and publish its public guidelines for use - they can vote along with the FDA's labeled indication for population, or decide upon their own, which is rare (though it nearly happened with Pfizer's booster, as the CDC's independent advisory panel recommended broader usage than the labeled indication, but the CDC chief overrode them and stuck to the FDA label).
Though the FDA's label for the Moderna and J&J's booster are somewhat broader in population than Pfizer, the FDA still provided restrictions on who can get the vaccine.
However, the FDA's independent advisory panel voted unanimously to move towards vaccinating the general public with boosters of all three vaccines possibly in November.
The reason for this broadening of population since Pfizer's authorization is because Moderna's study was a larger and more comprehensive than Pfizer's, definitively proving not only that the efficacy of all 3 vaccines wane over time, with J&J's vaccine waning the fastest, and Moderna's lasting the longest.
There was some evidence that a third booster of Moderna improved immunity at least temporarily (however, we don't know for exactly how long yet, that will take a phase 4 real-world data study after the initial clinical trial).
HOWEVER, in addition to not having longer-term efficacy data on the boosters, there have been no studies on the safety of mix-and-matching, we're just assuming based on waning immunity, so this is pretty shaky, not-entirely-data-based ground we're walking on - but Moderna's study did definitively prove what the Pfizer study did not - that the efficacy of the first rounds do indeed wane over time.
Thus, I want Moderna, I always did lol.
However, good luck getting it, here in Kentucky - they ran out before they got to my age group, the first go round :/