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Data source: VAERS (Vaccine Adverse Event Reporting System)

Data through 2026 · Updated quarterly

Built by TheDataProject.ai · © 2026 VaccineWatch

Important: VAERS accepts reports of adverse events following vaccination. For any given report, there is no certainty that the reported event was caused by the vaccine. Reports may contain information that is incomplete, inaccurate, coincidental, or unverifiable. Most reports to VAERS are voluntary, which means they are subject to biases. This data cannot be used to determine if vaccines cause or contribute to adverse events.

⚠️

Important: VAERS reports alone cannot determine if a vaccine caused an adverse event. Reports may contain incomplete, inaccurate, or unverified information. Correlation does not equal causation.

  1. Home
  2. Vaccine Side Effects
  3. Tdap Vaccine
5 min read
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Tdap Vaccine Side Effects

Tdap (tetanus, diphtheria, pertussis) is recommended for all adolescents and adults, and during every pregnancy. As one of the most commonly administered vaccines, it generates significant VAERS reports.

52,846
Total Reports
129
Deaths Reported
2,191
Hospitalizations
14,141
ER Visits

Most Commonly Reported Side Effects

The following symptoms are most frequently reported after vaccination:

#{i + 1}Injection site erythema
8,820
#{i + 1}Injection site pain
7,312
#{i + 1}Pyrexia
7,220
#{i + 1}Injection site swelling
7,034
#{i + 1}Pain
6,345
#{i + 1}Erythema
5,902
#{i + 1}Pain in extremity
5,693
#{i + 1}Headache
5,500
#{i + 1}Dizziness
4,989
#{i + 1}Nausea
4,529
#{i + 1}Injection site warmth
4,040
#{i + 1}Syncope
3,189

Tdap During Pregnancy

Tdap is recommended during weeks 27-36 of every pregnancy to protect newborns from whooping cough (pertussis). This means a large portion of Tdap VAERS reports come from pregnant women, which may include pregnancy complications that arecoincidental rather than vaccine-caused.

Large-scale studies have found Tdap during pregnancy to be safe, with no increased risk of major birth defects, preterm birth, or small-for-gestational-age births.

Expected Side Effects

Common:

  • Pain, redness, or swelling at injection site (very common)
  • Fatigue and body aches
  • Headache
  • Nausea
  • Fever (usually low-grade)

Less common:

  • Extensive limb swelling (more common in children with multiple DTaP doses)
  • Joint pain

Rare:

  • Guillain-Barré Syndrome (very rare, about 1 per million)
  • Severe allergic reaction

Tdap is recommended for adolescents, adults, and during every pregnancy. See timing on the CDC vaccine schedule and our 2026 vaccine schedule analysis.

⚠️ Remember: VAERS reports show correlation, not causation. A report filed after vaccination doesn't mean the vaccine caused the reported event. Always consult your healthcare provider for medical advice.

Explore This Data

Tdap Vaccine Detail →
Full VAERS profile
Birth Defects Analysis →
Pregnancy-related data
All Side Effects →
Overview across all vaccines

2026 Safety Monitoring Update

As of mid-2026, the Tdap vaccine continues to be monitored through VAERS and complementary surveillance systems including the Vaccine Safety Datalink (VSD) and the Clinical Immunization Safety Assessment (CISA) project. No new safety signals have been identified in recent data that would change the established safety profile of this vaccine.

The HHS administration's announced development of AI-powered VAERS analysis tools may provide additional insights into Tdap vaccine adverse event patterns. These tools aim to detect subtle signals that traditional statistical methods might miss, though their implementation timeline and methodology remain under development.

It's worth noting that VAERS reporting for routine vaccines like Tdap has remained stable through the post-pandemic period. While COVID-19 vaccine reports surged and then declined, reporting patterns for established childhood and adult vaccines have been remarkably consistent, suggesting that the VAERS system continues to function as designed for ongoing safety surveillance.

Understanding VAERS Data for Tdap

When interpreting VAERS data for Tdap vaccines, several key principles apply:

  • Reports ≠ Causation: A VAERS report means an event occurred after vaccination. It does not establish that the vaccine caused the event. Many reported symptoms are common health occurrences that would happen regardless of vaccination.
  • No denominator: VAERS does not track the number of doses administered. Without knowing how many people received the vaccine, raw report counts cannot be used to calculate risk rates or compare safety across vaccines.
  • Co-administration: Many vaccines are given at the same visit. When a VAERS report lists multiple vaccines, it's impossible to determine which vaccine (if any) was responsible for the reported adverse event.
  • Reporting variability: Healthcare provider awareness, media attention, and public concern all influence how many reports are filed. Changes in report volume may reflect changes in reporting behavior rather than changes in actual safety.

How to Use This Data Responsibly

VAERS data is most useful as a starting point for conversation with your healthcare provider, not as a basis for medical decisions. If you're concerned about Tdap vaccine side effects:

  • Discuss your specific risk factors with your doctor or pharmacist
  • Ask about the relative risks of the disease the vaccine prevents vs. the vaccine itself
  • Consider your age, health status, and any previous vaccine reactions
  • Remember that clinical trials and post-market studies provide much stronger safety evidence than VAERS alone

For the most up-to-date safety information, consult the CDC's vaccine information pages or speak with a qualified healthcare professional.

More Resources

When Do Side Effects Start?
73% occur within 3 days of vaccination
Serious vs Non-Serious Outcomes
The full severity spectrum in VAERS
Report an Adverse Event
How to file a VAERS report
Our Methodology
How we process VAERS data

2026 Safety Monitoring Update

As of mid-2026, the Tdap vaccine continues to be monitored through VAERS and complementary surveillance systems including the Vaccine Safety Datalink (VSD) and the Clinical Immunization Safety Assessment (CISA) project. No new safety signals have been identified in recent data that would change the established safety profile of this vaccine.

The HHS administration's announced development of AI-powered VAERS analysis tools may provide additional insights into Tdap vaccine adverse event patterns. These tools aim to detect subtle signals that traditional statistical methods might miss, though their implementation timeline and methodology remain under development.

It's worth noting that VAERS reporting for routine vaccines like Tdap has remained stable through the post-pandemic period. While COVID-19 vaccine reports surged and then declined, reporting patterns for established childhood and adult vaccines have been remarkably consistent, suggesting that the VAERS system continues to function as designed for ongoing safety surveillance.

Understanding VAERS Data for Tdap

When interpreting VAERS data for Tdap vaccines, several key principles apply:

  • Reports ≠ Causation: A VAERS report means an event occurred after vaccination. It does not establish that the vaccine caused the event. Many reported symptoms are common health occurrences that would happen regardless of vaccination.
  • No denominator: VAERS does not track the number of doses administered. Without knowing how many people received the vaccine, raw report counts cannot be used to calculate risk rates or compare safety across vaccines.
  • Co-administration: Many vaccines are given at the same visit. When a VAERS report lists multiple vaccines, it's impossible to determine which vaccine (if any) was responsible for the reported adverse event.
  • Reporting variability: Healthcare provider awareness, media attention, and public concern all influence how many reports are filed. Changes in report volume may reflect changes in reporting behavior rather than changes in actual safety.

How to Use This Data Responsibly

VAERS data is most useful as a starting point for conversation with your healthcare provider, not as a basis for medical decisions. If you're concerned about Tdap vaccine side effects:

  • Discuss your specific risk factors with your doctor or pharmacist
  • Ask about the relative risks of the disease the vaccine prevents vs. the vaccine itself
  • Consider your age, health status, and any previous vaccine reactions
  • Remember that clinical trials and post-market studies provide much stronger safety evidence than VAERS alone

For the most up-to-date safety information, consult the CDC's vaccine information pages or speak with a qualified healthcare professional.

More Resources

When Do Side Effects Start?
73% occur within 3 days of vaccination
Serious vs Non-Serious Outcomes
The full severity spectrum in VAERS
Report an Adverse Event
How to file a VAERS report
Our Methodology
How we process VAERS data

More Side Effect Guides

All Vaccine Side Effects
Overview across all vaccines
COVID-19 Side Effects
1.1M+ reports analyzed
Full Dashboard
All 104 vaccines compared