Thursday, October 29, 2009

Most Patients With Vaccine Allergy May Be Safely Vaccinated

From Medscape Medical News
Laurie Barclay, MD

October 20, 2009 — Most patients with vaccine allergy may be safely vaccinated, according to a practice parameter published in the October issue of the Annals of Allergy, Asthma & Immunology. However, the new guidelines also recommend that patients with suspected allergy to vaccines or vaccine components be evaluated by an allergist or immunologist vs simply avoiding future immunizations, which could leave patients at higher risk for infectious disease.

Specific summary statements in the parameter include the following:

Mild local reactions, fever, and other constitutional symptoms after vaccinations occur often and are not a contraindication to subsequent doses.
Anaphylactic reactions after vaccination are rare, with incidence of approximately 1 per million doses.
Even if the vaccine is not clearly the cause, all serious events occurring after vaccine administration should be reported to the Vaccine Adverse Event Reporting System.
Measurement of IgG antibody levels to the immunizing antigen in a vaccine suspected of causing a serious adverse reaction can determine if levels are protective and whether subsequent doses are needed.
Ideally, all suspected anaphylactic reactions to vaccines should be evaluated so that the responsible allergen may be identified.
Gelatin, egg protein, or other vaccine components are more likely than the immunizing agent itself to cause IgE-mediated reactions to vaccines.
Immediate-type allergy skin testing should be performed in patients who appear to have had an anaphylactic reaction after vaccination. This testing should help confirm that the reaction was IgE mediated and identify the responsible vaccine component.
If the intradermal skin test result is negative, it is extremely unlikely that the patient has IgE antibody to any vaccine component, and the patient can be vaccinated in the usual manner.
In a patient with a history suggesting anaphylactic reaction, however, it is prudent to vaccinate with the patient under observation and to have epinephrine and other emergency treatment available.
In patients with history and skin tests results suggesting an IgE-mediated reaction to a vaccine but who need additional doses of the suspected vaccine or other vaccines with shared ingredients, the clinician can consider administering the vaccine in graded doses while observing the patient.
There are other less common but more serious reactions to vaccines, but only a few represent absolute contraindications to future doses.
Pregnant women should not be given live vaccines.
Live vaccines should generally not be given to immunocompromised persons.
Epidemiologic studies have not supported associations between specific vaccines or vaccination in general with long-term sequelae such as atopy, autism, and multiple sclerosis.
"The 2 key points of the practice parameter are that (1) patients with suspected allergy to vaccines or vaccine components should be evaluated by an allergist/immunologist and (2) most patients with suspected allergy to vaccines can receive vaccination safely," the guidelines authors conclude.

Ann Allergy Asthma Immunol. 2009;103:S1-14.

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