The bruise was the injection site administered by a pharmacy tech at Walgreens. Can't remember how far away my arm was from the side, so it's possible that the bursa was irritated. Appears to be 3 cm below the lower edge of the acromion, though I think it should be 5-6 cm to avoid the bursa. Any nurses care to comment? I know that you would get your vaccines at the hospital, but would you go back to a Walgreens for shots?