My 87 year old dad, who is on blood thinning medication, and my 80 year old mom, had no reactions to their Covid Vaccines. No rash, no sore arms... They both had the Moderna one.
I got first Moderna jab 2/26, my arm around the injection site was sore for 2-3 days, but no rash.
My girlfriend had almost no reaction to the first Moderna shot, but the second one kicked her butt for 2 days. She said it was equivalent to the worst flu she had ever had.