First AZ dose in late March, sore arm for 24 hours then back to normal. No big deal. My wife had it a week later (we're both late 40s - was before the <50 recommendation) and she was knocked flat for 2 days. Slept all day, sore muscles, chills. Took a full 3 days for her to be properly back to normal. 19 year old son had it and just had the sore arm for a day.