From the Guidelines
Allergic reactions to the Tdap (Tetanus, Diphtheria, and Pertussis) vaccine are rare, with severe allergic reactions, such as anaphylaxis, occurring in approximately 1 to 6 cases per million doses administered, as reported in the most recent and highest quality study 1.
Key Points
- The frequency of allergic reactions to Tdap vaccine is low, with severe reactions being extremely rare.
- Severe allergic reactions, such as anaphylaxis, are a contraindication to further vaccination with any component of the Tdap vaccine.
- Mild reactions, such as pain, redness, or swelling at the injection site, are more common and affect about 2 out of 3 people who receive the vaccine.
- Fever, headache, fatigue, or nausea may occur in about 1 in 4 recipients, but these are not allergic reactions.
Recommendations
- People with a history of severe allergic reaction to a previous dose of Tdap or any of its components should not receive the vaccine.
- Individuals with a history of anaphylaxis to components included in all Tdap and Td vaccines should be referred to an allergist to determine whether they have a specific allergy to tetanus toxoid and can be desensitized to tetanus toxoid.
- The low rate of allergic reactions is due to the vaccine's refined manufacturing process and extensive safety testing.
- If concerned about potential allergic reactions, discuss medical history with a healthcare provider before receiving the Tdap vaccine.
Important Considerations
- True allergic reactions typically involve symptoms like hives, swelling of the face or throat, difficulty breathing, dizziness, or rapid heartbeat occurring within minutes to hours after vaccination.
- Rashes that are macular, papular, petechial, or urticarial and appear hours or days after a dose of Tdap are frequently antigen-antibody reactions of little consequence or are due to other causes, such as viral illnesses.
- There is no evidence for a causal relation between Tdap vaccination and hemolytic anemia or thrombocytopenic purpura, as reported in earlier studies 1.
From the Research
Allergic Reactions to Tdap Vaccine
- The frequency of allergic reactions to vaccines, including Tdap, is rare, with an estimated rate of 0.65-1.45 cases per million vaccine doses 2.
- Anaphylactic reactions to vaccines, including Tdap, are also rare, with an estimated incidence of 1.3 per million vaccine doses administered for all vaccines 3.
- Allergic reactions to childhood vaccinations, including Tdap, can be induced by the microbial antigens, toxoids, and also by residual proteins which are derived from cultures media and stabilizers 4.
- The most common symptoms of anaphylaxis, a life-threatening systemic reaction, include urticaria, difficulty breathing, and mucosal swelling 5.
Management of Allergic Reactions
- Evaluation of patients with suspected vaccine reactions should begin by determining whether the symptoms and timing of the reaction were consistent with a true allergic reaction 6.
- Skin and serologic testing to vaccines and vaccine constituents can then be performed to further assess the potential cause of the reaction and to develop a plan for future immunizations 6.
- Acute management of anaphylaxis involves removal of the trigger, early administration of intramuscular epinephrine, and supportive care for the patient's airway, breathing, and circulation 5.
Risk Factors and Prevention
- Coexisting asthma, mast cell disorders, older age, underlying cardiovascular disease, peanut and tree nut allergy, and drug-induced reactions are associated with severe or fatal anaphylactic reactions 5.
- Patients should be monitored for a biphasic reaction (i.e., recurrence of anaphylaxis without reexposure to the allergen) for four to 12 hours, depending on risk factors for severe anaphylaxis 5.
- Following an anaphylactic reaction, management should focus on developing an emergency action plan, referral to an allergist, and patient education on avoidance of triggers and appropriate use of an epinephrine auto-injector 5.