By: Jackson, Lisa A. ; Peterson, Do ; Nelson, Jennifer C.
A retrospective cohort study of 1.3 million children ages one to six years in the Vaccine Safety Datalink population who received 6 million intramuscular (IM) vaccines from 2002 to 2009 aimed to determine whether medically attended local reactions to IM vaccines vary by injection site. Researchers looked at the inactivated influenza, hepatitis A, and DTaP vaccines, as they are usually administered alone. They found no difference in risk of medically attended local reaction with arm versus thigh injections for the inactivated influenza and hepatitis A vaccines, but they found a significantly lower risk of these events with thigh injections for the DTap vaccine among children ages 12 to 35 months. Their findings for the DTaP vaccine support recommendations that children under three years receive IM vaccinations in the thigh.