General Best Practice Guidelines for Immunization: Appendix 1: Glossary 193

Appendix 1: Glossary

Adverse event. An undesirable medical condition that occurs following vaccination 

which might be truly caused by a vaccine, or it might be pure coincidence. 

Adverse reaction. An undesirable medical condition that has been demonstrated to 

be caused by a vaccine. Evidence for the causal relation is usually obtained through 

randomized clinical trials, controlled epidemiologic studies, isolation of the vaccine 

strain from the pathogenic site, or recurrence of the condition with repeated 

vaccination (i.e., rechallenge); synonyms include side effect and adverse effect.

Adjuvant. A vaccine component distinct from the antigen that enhances the immune 

response to the antigen.

Antitoxin. A solution of antibodies against a toxin. Antitoxin can be derived from 

either human (e.g., tetanus immune globulin) or animal (usually equine) sources (e.g.,

diphtheria and botulism antitoxin). Antitoxins are used to confer passive immunity 

and for treatment.

Hyperimmune globulin (specific). Special preparations obtained from blood 

plasma from donor pools preselected for a high antibody content against a specific 

antigen (e.g., hepatitis B immune globulin, varicella-zoster immune globulin, rabies 

immune globulin, tetanus immune globulin, vaccinia immune globulin, 

cytomegalovirus immune globulin, botulism immune globulin).

Immune globulin. A sterile solution containing antibodies, which are usually 

obtained from human blood. It is obtained by cold ethanol fractionation of large pools 

of blood plasma and contains 15%-18% protein. Intended for intramuscular 

administration, immune globulin is primarily indicated for routine maintenance of 

immunity among certain immunodeficient persons and for passive protection against 

measles and hepatitis A.
General Best Practice Guidelines for Immunization: Appendix 1: Glossary 194

Immunization. The process of inducing or providing immunity by administering an 

immunobiologic. Immunization can be active or passive. Active immunization is the 

production of antibody or other immune responses through administration of a 

vaccine or toxoid. Passive immunization means the provision of temporary immunity 

by the administration of preformed antibodies. 

Immunobiologic. Antigenic substances (e.g., vaccines and toxoids) or antibodycontaining preparations (e.g., globulins and antitoxins) from human or animal donors. 

These products are used for active or passive immunization or therapy. Examples of 

immunobiologics include antitoxin, immune globulin and hyperimmune globulin, 

monoclonal antibodies, toxoids, and vaccines.

Intravenous immune globulin. A product derived from blood plasma from a donor 

pool similar to the immune globulin pool, but prepared so that it is suitable for 

intravenous use. Intravenous immune globulin is used primarily for replacement 

therapy in primary antibody-deficiency disorders, for treatment of Kawasaki disease, 

immune thrombocytopenic purpura, hypogammaglobulinemia in chronic lymphocytic 

leukemia, and certain cases of human immunodeficiency virus infection (Table 3-6).

Monoclonal antibody. An antibody product prepared from a single 

lymphocyte clone, which contains only antibody against a single antigen.

Simultaneous. In the context of vaccine timing and spacing, occurring on the 

same clinic day, at different anatomic sites, and not combined in the same syringe.

Toxoid. A modified bacterial toxin that has been made nontoxic, but retains the ability 

to stimulate the formation of antibodies to the toxin.

Vaccination. The physical act of administering any vaccine or toxoid. 

Vaccine. A suspension of live (usually attenuated) or inactivated microorganisms (e.g., 

bacteria or viruses) or fractions thereof administered to induce immunity and prevent 

infectious disease or its sequelae. Some vaccines contain highly defined antigens (e.g., 

the polysaccharide of Haemophilus influenzae type b or the surface antigen of hepatitis 

B); others have antigens that are complex or incompletely defined (e.g., Bordetella 

pertussis antigens or live, attenuated viruses).