News Author: Laurie Barclay, MD
CME Author: Charles P. Vega, MD
Adverse events associated with vaccines are rare and are frequently transient. For example, transient rash may occur in 3% to 5% of persons receiving the measles and varicella vaccines, and these rashes can resemble those of clinical measles or varicella. The MMR vaccine can also promote thrombocytopenia, which does not usually lead to clinical consequences. The rubella vaccine causes acute arthritis among approximately 15% of women.
Other adverse events, such as encephalopathy with pertussis vaccination or Guillain-Barré syndrome after influenza vaccine, are quite serious but are also so rare that an exact estimate regarding their prevalence is difficult. Allergic reactions to vaccination could also be included in this rare-but-serious category, and the current practice parameter suggests the best strategy in caring for a patient with suspected allergy to a vaccine.
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.
The new recommendations were issued by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma and Immunology; the American College of Allergy, Asthma and Immunology; and the Joint Council of Allergy, Asthma and Immunology.
"Local, injection site reactions and constitutional symptoms, especially fever, are common after vaccinations and do not contraindicate future doses," chief editor John M. Kelso, MD, from the Division of Allergy, Asthma & Immunology at Scripps Clinic in San Diego, California, said in a news release.
Guidelines Not Provided in Other Reviews
The practice parameter contains detailed and specific guidelines not contained in previously published reviews. It offers a practical, peer-reviewed, evidence-based guide to assist primary care clinicians as well as specialists in allergy and immunology in assessing and treating patients with suspected allergy to vaccines.
The guidelines provide general and vaccine-specific recommendations for skin testing to vaccines and components, serum-specific immunoglobulin E (IgE) in vitro antibody testing, serologic testing for protective antibody responses to vaccines, vaccine administration, and avoidance. If this practice parameter is implemented, most patients who avoid vaccination because of allergy concerns will be able to be vaccinated appropriately.
Of approximately 235 million doses of vaccines given annually in the United States, only 1 dose per million causes anaphylaxis. Furthermore, death caused by vaccine-induced anaphylaxis is extremely uncommon.
The guidelines recommend reporting all serious events after vaccination to the Vaccine Adverse Event Reporting System of the Centers for Disease Control and Prevention and US Food and Drug Administration.
Patients with suspected anaphylactic reactions to vaccines should be examined by an allergist to identify the allergen responsible for IgE-mediated reaction and to recommend optimal treatment. Typically, the responsible allergen is one of the vaccine components vs the specific antigen needed for immunization. Potentially allergenic vaccine components may include gelatin, egg protein, rarely yeast, latex from the vial stopper or syringe plungers, neomycin, or thimerosal.
"Gelatin, which is added to many vaccines as a stabilizer, is either bovine or porcine, which are extensively cross-reactive," Dr. Kelso said. "We recommend that a history of allergy to the ingestion of gelatin should be sought before administering a gelatin-containing vaccine....However rare, if a patient gives a history of an immediate-type reaction to yeast, latex, neomycin or thimerosal, we recommend that it be investigated with skin testing before immunization with a vaccine containing these constituents."
Skin testing may include prick test with full-strength vaccine (or diluted vaccine if there is a history of life-threatening reaction). If results of the prick test with full strength vaccine are negative, intradermal testing can be performed with 0.02-mL vaccine 1:100. Skin tests to vaccine components may include prick tests with commercial extracts of whole egg or egg white (influenza and yellow fever vaccines), chicken (yellow fever vaccine), or Saccharomyces cerevisiae yeast (hepatitis B vaccine and human papillomavirus vaccine).
"The MMR (measles and mumps vaccines) and one type of rabies vaccine contain negligible or no egg protein, and can be administered to egg allergic children without prior skin testing," Dr. Kelso said. "Egg protein is present in higher amounts in yellow fever and influenza vaccines and may cause reactions in egg-allergic patients, who should be evaluated by an allergist prior to receiving these vaccines."
A prick test with sugared gelatin may be useful if allergic reactions develop after administration of vaccines that contain gelatin, including some brands of diphtheria and tetanus toxoids and acellular pertussis (DTaP), rabies or influenza, Japanese encephalitis, measles, mumps, rubella, varicella, yellow fever, and zoster.
"Persons with a history of allergy to egg or a past reaction to an influenza vaccine may still be able to receive the H1N1 vaccine or the seasonal flu vaccine safely," said co-chief editor James T. Li, MD, Mayo Clinic professor of medicine and chair, Division of Allergy and Immunology. "I believe that anyone with this concern should check with their doctor and consult with an allergist."
Summary Statements in the Parameter
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.