Vaccination related shoulder injuries in children are more common. Accidental injection of a vaccine near shoulder joint can trigger an immune response affecting the function of the shoulder joint in children. This condition is called shoulder injury related to vaccine administration (SIRVA). It is recommended that ideal site for intramuscular injections in infants less than 12 months is the thigh muscle. The length of the needle is also important to prevent injury to the surrounding area and it depends on the injection site and age of the child.