I think this makes great sense at the world population level. And after all, the Pfizer vaccine is only 30μg per dose, with equivalent (marginally higher) effic

I think this makes great sense at the world population level. And after all, the Pfizer vaccine is only 30μg per dose, with equivalent (marginally higher) efficacy at preventing disease. The RNA sequences are highly similar as well, so I doubt that one expresses much more robustly. It’s been long speculated that the moderna vaccine has more side effects with same efficacy due to the aggressive dosing, and reducing to 50μg or even 25 is supported by a plethora of reasonable data.