My first two COVID-19 vaccines were Pfizer. When I got my booster last week, I chose Moderna. Actually, the nurses asked me if Moderna was okay, I said "sure, whatever." lol
I didn't feel much or very little side effects after my Pfizer shots. But, the day after my Moderna booster, I got a big headache and really bad vertigo. I had to work that day, so I wasn't really able to do much. Luckily, 2 things -- 1) I was in the office by myself because everyone in the office is WFH and 2) it was the day before Thanksgiving, so nothing much was going on anyways.
It wasn't until I got home and took some aspirin before I started feeling better.