I'll get it when it's my turn. Apparently, the efficacy goes back up to like 95% even against Delta. So it seems like a major driver of breakthrough infections has been waning immunity.
Moderna, probably because the doses were higher, has held up better than Pfizer. And although similar, the theory is mixing vaccines provides some enhanced protection. But I've not seen any definitive research addressing that question.
I had chills & low-grade fever after the second Pfizer dose. So I will almost certainly NOT switch to Moderna for the booster.
If the booster shots are as bad as the second round for many people, much less worse, then buckle up. Also, WTF even Russia doesn't have vaccine mandates.