IM injections should be given with the needle at a 90º angle to the skin and the
skin should be stretched, not bunched. Deep SC injections should be given
with the needle at a 45º angle to the skin and the skin should be bunched, not
stretched. It is not necessary to aspirate the syringe after the needle is
introduced into the muscle (WHO, 2004; Plotkin and Orenstein, 2004).