Childhood immunizations have reduced the incidence of many infectious diseases. The global eradication of smallpox in 1977 and the eradication of poliomyelitis from North and South America are both examples of the successful use of immunizations. Vaccine response is determined by the antigen’s chemical and physical nature, mode of administration, and host factors.

In addition to the proper storage and handling of vaccines, it is important to use the proper technique for vaccine administration (Table 96.1). The current routes of immunization are oral, intranasal, and parenteral. The primary route for vaccines is parenteral, either intramuscular or subcutaneous, depending on the method that demonstrates maximum efficacy and safety. Live vaccines, such as polio, can be given orally. This enables replication at the mucosal surfaces and the induction of secretory immunoglobulin A. However, currently, inactivated poliovirus is recommended for use in the United States. The live-attenuated influenza vaccine is the only approved intranasal vaccine.

In addition to the route of administration, the appropriate site and needle size should be determined for age. The anterolateral thigh and deltoid are commonly used sites. Vaccines with adjuvants such as aluminum need to be injected deep into the muscle. The American Academy of Pediatrics’ Redbook 2006, outlines the recommended site and needle size for intramuscular administration of commonly used vaccines. Subcutaneous vaccines can be administered in the pinched-fold of the anterolateral outer thigh or upper outer triceps at a 45-degree angle. Multiple vaccines can be given simultaneously, but at least 1 inch apart. In the event of a local reaction, this will facilitate the identification of the causative agent. When vaccines are given inappropriately, their efficacy can be decreased. For example, hepatitis B vaccine should be given intramuscularly in the deltoid muscle;

subcutaneous administration in the buttocks has been shown to lower seroconversion rates.