Merck Manual

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Passive Immunization


Margot L. Savoy

, MD, MPH, Lewis Katz School of Medicine at Temple University

Reviewed/Revised Jul 2023
Topic Resources

Passive immunization involves giving antibodies to an organism or to a toxin produced by an organism.

Passive immunization is provided in the following circumstances:

  • When people cannot synthesize antibody

  • When people have been exposed to a disease that they are not immune to or that is likely to cause complications

  • When people have a disease and the effects of the toxin must be ameliorated

Passive immunization does not induce natural immunity.

(See table .)


Human immune globulin (IG)

IG is a concentrated antibody-containing solution prepared from plasma obtained from normal donors. It consists primarily of IgG, although trace amounts of IgA, IgM, and other serum proteins may be present. IG very rarely contains transmissible viruses (eg, hepatitis B or C, HIV) and is stable for many months if stored at 4° C. IG is given intramuscularly (IM).

Because maximal serum antibody levels may not occur until about 48 hours after IM injection, IG must be given as soon after exposure as possible. Half-life of IG in the circulation is about 3 weeks.

IG may be used for prophylaxis in people exposed to or at risk of

IG provides only temporary protection; the antibody content against specific agents varies by as much as 10-fold among preparations. Administration is painful, and anaphylaxis can occur.

IV immune globulin (IVIG) was developed to provide larger and repeated doses of human immune globulin. IVIG is used to treat or prevent severe bacterial and viral infections, autoimmune disorders, and immunodeficiency disorders, particularly the following:

Adverse effects of IVIG are uncommon, although fever, chills, headache, faintness, nausea, vomiting, hypersensitivity, anaphylactic reactions, coughing, and volume overload have occurred.

Subcutaneous immune globulin (SCIG) is also prepared from pooled human plasma; SCIG is intended for home use in patients with a primary immunodeficiency.

Injection site reactions are common, but systemic adverse effects (eg, fever, chills) are much less common with SCIG than with IVIG.

Hyperimmune globulin

Hyperimmune globulin is prepared from the plasma of people with high titers of antibody against a specific organism or antigen. It is derived from people convalescing from natural infections or donors artificially immunized.

Hyperimmune globulins are available for

Administration is painful, and anaphylaxis may occur.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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