Same here: mild muscle ache for the Pfizer booster. If I didn't know I'd had the booster the previous day, I would have attributed it to falling asleep on a lumpy part of my comforter or something, assuming I'd even noticed it at all.

My understanding is the Moderna booster, being a 1.5x dose, often results in stronger side effects that knock a person out more often.

The Moderna booster is actually a half dose, although I don't know if it tends to have stronger side effects than the first two full doses.

Source: https://www.fda.gov/news-events/press-announcements/coronavi...

It's half the giant Moderna dose (100 mcg / 2 = 50 mcg), and 60% more than the standard/booster Pfizer dose (30 mcg).

Experience varies among the population. I had no notable side effects for the first 2 Pfizer shots but 3rd one had me in bed for 48 hours.

Same (pfizer) and this was the typical reaction in friends and family. A couple had minor flu-like symptoms for an afternoon but nothing like some have described here (days of "agony" etc), totally unheard of in my circles.