Did the increased rhr go away quickly for you? Same timing as your other side effects? Been putting off my booster since I also experienced the increased heart rate for 12 hrs straight after my 2nd Pfizer and I hadn’t heard of anyone else having this side effect. It was up for me to around 80-85 (normally 65-70ish), jumping up to over 100 just walking across the room. I also had a bad headache which went away when my rhr returned to normal.Similar experience here yesterday at the other end of the UK. No real wait. Got Pfizer in my case. Felt a little different afterwards from the AZ's I had previously. Actually had quite a sore arm yesterday and this morning started to get that grotty feeling like I'm coming down with something but it's fading tonight. (Interestingly my rhr on my watch has been up all day from what I'd normally expect.)