Vaccine allergy

BACKGROUND

Patients receive vaccines to prevent infections and diseases from developing. Although rare, some patients may develop allergic reactions to vaccines. This may occur when an individual is allergic to one or more products contained in the vaccine. Most allergic reactions occur if the vaccine contains antibiotics, egg proteins, gelatin, or mercury.

Vaccines work by stimulating the body's immune system. Vaccines contain small amounts of disease-causing organisms that allow the immune system to produce antibodies to the foreign invader. Once antibodies are developed, the immune system is able to respond quickly to the infection if the disease-causing organism ever enters the body. Consequently, individuals become immune to the specific illness after receiving a vaccine.

Some vaccines require more than one shot to take affect. Some vaccines may contain live viruses or bacteria that have been weakened, while others may contain inactivated (killed) microorganisms.

Live, weakened vaccines, also called attenuated vaccines, contain disease-causing organisms. These organisms have been grown in a laboratory so that they are unable to actually infect the human patient. However, in rare instances, the vaccine may infect the recipient or those who come into close contact with a recently vaccinated individual. This is more likely to occur in individuals who have extremely weakened immune systems (such as chemotherapy or HIV/AIDS patients). In general, live vaccines, such as those for yellow fever and measles, mumps, and rubella (MMR), have shown to produce stronger immune responses than inactivated vaccines. Some patients may only need one shot to produce life-long immunity.

Other vaccines, such as the influenza (flu) and cholera vaccines, contain microorganisms that have been killed with chemicals or heat. In general, these vaccines induce an incomplete or short-lived immune response. Therefore, patients usually need to receive booster shots (additional doses of the vaccine to enhance its effectiveness). These vaccines are generally safer than live vaccines because there is no chance that they will infect the patient.

Some types of vaccines only contain disease-causing toxins that are produced by bacteria. These vaccines do not contain any microorganisms. For example, the tetanus vaccine contains a bacterial toxin produced by tetanus bacteria. This toxin has been altered so that it will not cause disease in humans. Patients who receive this type of vaccine will become immune to the specific disease-causing toxin.

Accellular and subunit vaccines are made with just part of the bacteria or virus. For instance, the Haemophilus influenzae type B and hepatitis vaccines are produced this way.

People may develop allergic reactions to any type of vaccine and/or its components. The severity and duration of allergic reactions to vaccines vary among patients. Symptoms can develop anywhere from several minutes to several hours after the vaccine is administered. Anaphylaxis, a systemic allergic reaction that can cause low blood pressure, breathing difficulties, shock, and loss of consciousness, may occur. Anaphylaxis is considered a life-threatening emergency that requires immediate medical treatment.

Epinephrine is a medication used to treat anaphylaxis. Other medications, including antihistamines and corticosteroids, may help treat other allergic symptoms associated with vaccines.

CAUSES

Patients may develop an allergic reaction to a vaccine if the immune system overreacts to substances contained in the vaccine. Most allergic reactions occur when the vaccine contains antibiotics, egg proteins, gelatin, or mercury.

Typically, an allergic response is not triggered the first time the body encounters the allergen (substance that causes an allergic reaction). In fact, some people can be exposed to the allergen several times before an allergy develops. It is only after one or more episodes of exposure to an allergen that the immune system becomes sensitized. During this process, the body's white blood cells develop immunoglobulin E (IgE) antibodies to the allergens. Once sensitized, the antibodies quickly detect and bind to the allergens in the body.

After binding to allergens, antibodies trigger other immune cells to release chemicals (such as histamine) that cause allergic symptoms, such as runny nose, watery eyes, and sneezing, as well as anaphylaxis. Anaphylaxis is a severe allergic reaction that affects many parts of the body. Symptoms vary from mild to severe and may include breathing difficulties, shock, and loss of consciousness. Anaphylaxis is a potentially fatal reaction that requires immediate treatment.

ALLERGY TRIGGERS IN VACCINES

Antibiotics: Polio vaccines contain streptomycin, polymyxin B, and neomycin. In addition, the measles, mumps, rubella (MMR), and chickenpox vaccine also contain trace amounts of neomycin. Thus, these vaccines may cause an allergic reaction in people who are allergic to these antibiotics.

Patients who are allergic to antibiotics should consult their healthcare providers before receiving antibiotic-containing vaccines. Depending on the severity of the patient's history of allergic reactions, a healthcare provider may not recommend these vaccines.

One of the most common drug allergies occurs in response to penicillin. However, there are currently no vaccines made with penicillin or penicillin-related antibiotics.

Eggs: The current measles, mumps, and rubella (MMR) vaccine contains trace amounts of egg proteins, to which some patients may be allergic. However, according to the National Advisory Committee on Immunization, MMR can be administered safely to 99% of patients with egg allergies.

The influenza vaccine, also called the flu shot, also contains egg proteins. Patients who are allergic to eggs should not receive this vaccine because it contains enough egg protein to trigger a severe, life-threatening reaction called anaphylaxis. The most severe symptoms of anaphylaxis include low blood pressure, breathing difficulties, shock, and loss of consciousness, all of which can be fatal.

The yellow fever vaccine is also made with egg proteins. Yellow fever, an often fatal viral infection, is a major concern for patients living in or traveling to South America or Africa. Therefore, patients who are allergic to eggs and are planning to visit these areas should discuss their options with their healthcare providers. Usually, patients who are allergic to eggs receive lower doses of the vaccine over a longer period of time. The doses are gradually increased until the patient is able to take the full dose. This process is called desensitization because the body builds up a tolerance to the egg proteins.

Gelatin: Some live vaccines, including MMR, chicken pox, and yellow fever, contain gelatin. This ingredient helps to stabilize the vaccine. Patients who are severely allergic to gelatin should consult their healthcare providers before receiving such vaccines.

Mercury (thimerosal): Thimerosal is a mercury-containing preservative that was once commonly used in vaccines. This ingredient helps kill any live contaminants in vaccines. However, in rare cases, thimerosal may trigger minor allergic reactions in sensitive patients.

Although no serious side effects have been reported from thimerosal at doses used in vaccines, the Public Health Service (PHS) agencies, the American Academy of Pediatrics (AAP), and vaccine manufacturers have agreed that the ingredient should be reduced or eliminated in vaccines as a precautionary measure. Currently, most vaccines in the United States do not contain thimerosal.

SYMPTOMS

General: Allergic reactions to vaccines are rare, and symptoms can range from mild to severe. The most serious allergic reaction, called anaphylaxis, can be life threatening. Symptoms can develop anywhere from several minutes to several hours after the vaccine is administered.

Anaphylaxis (anaphylactic shock): Anaphylaxis is a systemic allergic reaction, which means that many parts of the body are affected. Symptoms of anaphylaxis can vary from mild to severe and may include low blood pressure, breathing difficulties, chest pain, hives, and loss of consciousness. The time lapse between contact with the allergen and anaphylactic symptoms varies among individuals. Symptoms may appear immediately or may be delayed from 30 minutes to one hour after exposure. Symptoms may also disappear and then recur hours later. Once symptoms arise, they progress quickly. Anyone with symptoms of anaphylaxis should seek immediate treatment.

Angioedema: Some hypersensitive patients may experience angioedema in response to a vaccine. Angioedema refers to the swelling that occurs in the tissue just below the skin. Angioedema is similar to hives, except it occurs deeper in the skin. The swellings, known as welts, usually appear around the eyes and mouth. They may also be present on the hands, feet, and throat.

Asthma: Asthma symptoms, including coughing, wheezing, shortness of breath, or difficulty breathing, may be triggered by vaccine allergies, especially in infants and young children.

Hives: Some patients may develop hives. Hives are red, itchy swollen welts on the skin that may appear suddenly and disappear quickly. They often develop in clusters, with new clusters appearing as other areas clear up.

DIAGNOSIS

General: Patients who have suspected allergies may undergo allergy testing to confirm a diagnosis. If a patient tests positive to vaccine allergens (substances that trigger an allergic reaction), the vaccine may not be recommended, or it may be given in low doses over a longer period of time.

Patients who experience symptoms of anaphylaxis after receiving a vaccine are treated with epinephrine immediately. Because anaphylaxis is life threatening, a diagnosis is not needed to begin urgent medical treatment. Less-severe allergic reactions to vaccines can be diagnosed with either a skin test or allergen-specific immunoglobulin (IgE) test.

Skin test: A skin test is used to determine whether a patient is allergic to certain allergens that are contained in vaccines. During the test, the skin is exposed to different allergens. The skin is then observed for an allergic reaction. If an allergen triggers an allergic reaction to a test, the patient will develop reddening, swelling, or a raised, itchy red wheal (bump) that looks similar to a mosquito bite. The healthcare provider will measure the size of the wheal and record the results. The larger the wheal, the more severe the allergy. A skin test is typically conducted in a healthcare provider's office. Skin tests cause minimal, if any, discomfort. The needles used barely penetrate the skin's surface and will not cause bleeding.

Allergen-specific immunoglobulin (IgE) test: An allergen-specific immunoglobulin E (IgE) test, commonly referred to as radioallergosorbent test (RAST©), may also be used to determine whether the patient is allergic to certain allergens in vaccines. However, this test is less accurate than a skin test. It is usually performed in patients who have coexisting severe skin diseases (such as eczema or psoriasis) that make it difficult to interpret a skin test.

During the procedure, a sample of blood is taken from the patient and sent to a laboratory that performs specific IgE blood tests. The allergen is bound to a paper disc called an allergosorbent. Then the patient's blood is added. If the blood contains immunoglobulin antibodies (substances that detect and bind to foreign substances in the body) to the allergen, the blood will bind to the allergen on the disc. A radiolabelled ANTI-IgE antibody is then added to the disc to measure the level of immunoglobulin E present in the blood. The higher the radioactivity, the higher the level of IgE in the blood and the more severe the allergy.

A qualified healthcare provider will interpret the results of the test. In general, the sensitivity of these tests ranges from 50-90%, with the average being about 70-75%. The patient will receive test results in about 7-14 days.

TREATMENT

General: Patients should tell their healthcare providers if they have any allergies, especially to foods or medications. Patients who experience symptoms of anaphylaxis should receive epinephrine as quickly as possible. Other medications, including antihistamines, and corticosteroids, may be used to treat less-severe allergic reactions.

Patients who experience an allergic reaction to vaccines should not receive the booster shot until allergy testing is performed. After allergy testing, a healthcare provider may recommend that the patient receive lower doses of the vaccine over a period of time. The doses are gradually increased until the patient is able to take the full dose. This process is called desensitization because the body builds up a tolerance to the allergens.

Antihistamines: Oral antihistamines like diphenhydramine (Benadryl©) have been used to reduce allergy symptoms. During a severe allergic reaction, diphenhydramine may be injected into the patient.

Corticosteroids: Corticosteroids may be injected into the vein to quickly relieve symptoms of severe allergic reactions. These drugs reduce swelling and many other symptoms of allergic reactions. Individuals may also need to take an oral corticosteroid, such as prednisone (Prednisone Intensol©, Sterapred©, or Sterapred© DS), for several days after the initial treatment. Oral steroids may also be given for patients who experience less severe reactions. Also, a corticosteroid cream, such as Hydrocortisone 1%), which is available over-the-counter, has been used to relieve swelling and itching associated with hives.

Epinephrine: Epinephrine is only used to treat very severe reactions, including anaphylaxis. Epinephrine is injected and acts as a bronchodilator because it opens the airways. It also constricts the blood vessels, which increases blood pressure. Patients who experience anaphylaxis may also be admitted to the hospital to have their blood pressure monitored and possibly to receive breathing support. Other emergency interventions may also include endotracheal intubation (placing a tube through the nose or mouth into the airway) or emergency surgery to place a tube directly into the trachea (tracheostomy or cricothyrotomy).

Individuals with a history of severe allergies should carry a prescription epinephrine auto-injector, called an EpiPen©. If symptoms of anaphylaxis appear after exposure to an allergen, the patient uses the device to inject the epinephrine into his/her thigh. A trained family member of friend may help the patient administer the epinephrine, if necessary.

Less severe allergic reactions that affect breathing may be treated with an inhaled epinephrine bronchodilator.

INTEGRATIVE THERAPIES

Note : Anaphylaxis is considered a medical emergency that requires immediate medical care. Therefore, integrative therapies should not be used in place of conventional medicine when an individual experiences symptoms of an anaphylactic reaction.

Unclear or conflicting scientific evidence :

Acupuncture : Acupuncture plus point-injection has been found beneficial for the treatment of hives, although more research is needed to confirm these findings.

Needles must be sterile in order to avoid disease transmission. Avoid with heart valve disease, infections, bleeding disorders or with drugs that increase the risk of bleeding (anticoagulants), medical conditions of unknown origin, and neurological disorders. Avoid on areas that have received radiation therapy and during pregnancy. Use cautiously with lung disease (such as asthma or emphysema). Use cautiously in elderly or medically compromised patients, diabetics, or with a history of seizures. Avoid electroacupuncture with irregular heartbeat or in patients with pacemakers.

Traditional or theoretical uses, which lack sufficient evidence :

Burdock : Traditionally, burdock has been used to treat hives. However, there is currently no human evidence on its safety and effectiveness for this use.

Avoid if allergic to burdock or other plants of the Asteraceae/Compositae family (ragweed, chrysanthemums, marigolds, daisies). Avoid with a history of dehydration, diabetes, heart disease, cancer, high blood pressure, or HIV. Stop use before surgeries/dental/diagnostic procedures. Avoid if pregnant or breastfeeding.

Chamomile : Although chamomile has traditionally been used to treat hives, scientific evidence is lacking. Currently, no human trials have evaluated the safety or effectiveness of chamomile for this use.

Avoid if allergic to chamomile or any related plants, such as aster, chrysanthemum, mugwort, ragweed, or ragwort. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Use cautiously if driving or operating machinery. Avoid if pregnant or breastfeeding.

Detoxification therapy (cleansing) : Detoxification has been suggested as a possible treatment for hives. However, there is currently no scientific evidence of its safety or effectiveness for this use.

In cases of illness, the various forms of detoxification should be used under professional guidance. See specific monographs for precautions and warnings associated with modalities of detoxification.

Kudzu : Traditionally, kudzu has been used to treat hives. However, there is currently no scientific evidence the safety and efficacy for this use.

Use cautiously with anticoagulants/anti-platelet and blood pressure lowering agents, hormones, antiarrhythmics, benzodiazepines, bisphosphonates, diabetes medications, drugs that are broken down by the liver's cytochrome P450 enzymes, mecamylamine, neurologic agents ,and methotrexate. No well-designed studies on the long-term effects of kudzu are available. Avoid if allergic or hypersensitive to Pueraria lobata or members of the Fabaceae/Leguminosae family. Avoid if pregnant or breastfeeding.

Moxibustion : There is limited evidence suggesting that moxibustion may help treat hives. Additional research is needed to evaluate the safety and efficacy of moxibustion for this use.

Use cautiously over large blood vessels and thin or weak skin. Avoid with aneurysms, any kind of "heat syndrome," heart disease, convulsions or cramps, diabetic neuropathy, extreme fatigue and/or anemia, fever, or inflammatory conditions. Do not use with skin conditions, ulcerated sores, or skin adhesions. Avoid areas with an inflamed organ, contraindicated acupuncture points, face, genitals, head, or nipples. Use cautiously in patients who have just finished exercising or taking a hot bath or shower. Use cautiously with elderly people with large vessels. Not advisable to bathe or shower for up to 24 hours after a moxibustion treatment. Avoid if pregnant or breastfeeding.

Peppermint oil : Historically, peppermint has been used to treat hives. Further research is needed to determine whether peppermint is safe and effective for this use.

Avoid if allergic or hypersensitive to peppermint or menthol. Peppermint is generally considered safe in non-allergic adults when taken in small doses. Use cautiously with G6PD deficiency or gallbladder disease. Menthol, which makes up part of peppermint oil, is generally considered safe in non-allergic adults. However, doses of menthol greater than one gram per kilogram of body weight may be deadly in humans. Avoid if pregnant or breastfeeding.

Probiotics : Although probiotics have been suggested as a possible treatment for hives, there is insufficient scientific evidence on its safety and efficacy for this use.

Probiotics are generally considered safe and well tolerated. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.

PREVENTION

Patients should tell their healthcare providers if they have any allergies, especially to foods or medications.

Individuals with a history of anaphylaxis should carry an autoinjectable epinephrine device (known as an EpiPen©) with them at all times. A trained family member or friend may help the patient administer the epinephrine, if necessary.

AUTHOR INFORMATION

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

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