DEAR DR. ROACH: I have notes from friends at home who are getting their COVID vaccines and high-dose flu shots on the same day in the same arm. They talk about being completely wiped out and the cons of having two sore arms. Does it matter if you get the shots in one arm or the other? I suspect that it’s fine to do them both in one arm, and there’s no advantage to dividing it over time or by arm. …