What are the common and serious adverse effects of the tetanus‑diphtheria‑acellular pertussis (Tdap) vaccine, its contraindications, and how should they be managed?

Tdap Vaccine Side Effects

The Tdap vaccine is generally well-tolerated with predominantly mild, self-limited local reactions; pain at the injection site is the most common side effect (occurring in 30-36% of recipients), while serious adverse events are rare. 1, 2

Common Local Reactions

Local injection site reactions are the most frequent adverse effects:

• Pain at injection site: Reported in 30.7% of adults receiving Tdap 3
• Swelling: Occurs in approximately 4% of recipients 3
• Redness/erythema: Affects 2-3% of vaccinees 3
• Increased arm circumference: Common in adolescents (≥15%) 2

These local reactions are typically mild and resolve within a few days without complications 4

Common Systemic Reactions

Systemic symptoms occur less frequently than local reactions:

• Headache: Reported in 15-20% of adults 2, 3
• Fatigue: Affects approximately 14-17% of recipients 2, 3
• Gastrointestinal symptoms: Common (≥15%) in adolescents and adults aged 19-64 years 2
• Myalgia (muscle pain): Occurs in 10-12.5% of vaccinees 3

The overall incidence rate of adverse events following immunization is 11.5 per 1000 vaccinated individuals 4

Serious Adverse Events (Rare)

While serious reactions are uncommon, clinicians must be aware of the following:

• Anaphylaxis: History of anaphylactic reaction to any vaccine component is an absolute contraindication 1, 2
• Guillain-Barré syndrome (GBS): If GBS occurred within 6 weeks of a previous tetanus toxoid-containing vaccine, the risk may be increased with subsequent doses 1, 2
• Arthus-type hypersensitivity reactions: Severe local reactions that require deferring vaccination for at least 10 years 1, 2
• Encephalopathy: Coma or prolonged seizures within 7 days of previous pertussis-containing vaccine is a contraindication to Tdap (but not Td) 1, 2

Absolute Contraindications

Do not administer Tdap in the following situations:

• Severe allergic reaction (anaphylaxis) to any vaccine component or previous dose 1, 2
• Encephalopathy (coma, decreased consciousness, or prolonged seizures) not attributable to another cause within 7 days of previous pertussis-containing vaccine 1, 2

Important note: All currently available Tdap vaccines contain polysorbate 80, so patients with confirmed polysorbate anaphylaxis require allergist referral and may need alternative strategies (Td or tetanus toxoid alone) 5

Precautions (Risk-Benefit Assessment Required)

Consider deferring or using alternative vaccines in these situations:

• Guillain-Barré syndrome <6 weeks after previous tetanus toxoid-containing vaccine 1
• Progressive or unstable neurologic disorder (including uncontrolled seizures or progressive encephalopathy) until condition stabilizes 1, 2
• Moderate or severe acute illness with or without fever until illness resolves 1
• History of Arthus reaction after previous tetanus or diphtheria toxoid-containing vaccine; defer until at least 10 years have elapsed 1, 2

Conditions That Are NOT Contraindications

The following should not prevent Tdap administration:

• Stable neurologic disorders including well-controlled seizures, resolved seizure disorder, or cerebral palsy 1, 6
• Mild acute illness without fever 1
• History of seizures (if well-controlled) 6
• Pregnancy: Tdap is recommended during each pregnancy, preferably at 27-36 weeks gestation, with excellent safety profile 1, 4

Management of Adverse Events

For common local and systemic reactions:

• Reassure patients that symptoms are typically mild and self-limited 4
• Acetaminophen may be used for symptomatic relief, and can be given prophylactically in patients with history of seizures 6
• Observe patients for 15 minutes post-vaccination for immediate allergic reactions 1

For serious adverse events:

• Report all clinically significant and serious adverse events to VAERS (Vaccine Adverse Event Reporting System) at https://vaers.hhs.gov 1
• Refer patients with suspected anaphylaxis to vaccine components to an allergist to determine if tetanus toxoid desensitization is possible 1, 5
• Document the specific reaction including timing, severity, and symptoms to guide future vaccination decisions 5

Special Populations

Pregnant women:

• Tdap during pregnancy (27-36 weeks) has an excellent safety profile with AEFI incidence of only 1.1 per 1000 4
• 91.4% had uncomplicated pregnancies and 98.7% of babies were born healthy 4
• Antibodies transfer to fetus via placenta and to infant via breast milk 7, 4

Elderly (≥65 years):

• Pain at injection site is the most common reaction (≥15%) 2
• Generally well-tolerated with lower rates of systemic symptoms compared to younger adults 2

Critical Pitfalls to Avoid

• Do not assume all reported "allergies" are true contraindications—many may not be anaphylaxis and proper evaluation is essential 5
• Do not delay allergist referral when vaccine component allergy is suspected, given the life-threatening nature of tetanus 5
• Do not confuse polysorbate with PEG allergy—these are distinct allergens requiring separate evaluation 5
• Do not use pediatric DTaP in adults or adolescents—it causes more severe local reactions than adult formulations 1, 8
• Do not defer tetanus protection due to pertussis component concerns—use Td instead if pertussis vaccination is contraindicated 1, 5