Question explored with the scientific record
TDap vaccine side effects adults
The short version: Tdap side effects in adults are common, mostly mild and short-lived, but the evidence on rare or serious harms is thin and comes from studies designed by the people who profit from the vaccine.
About 4 out of 5 adults who get Tdap report at least one side effect [14]. The most common is injection-site pain, which about 3 in 4 people get [3, 4]. Other frequent reactions include muscle aches (about 6 in 10), headache (about 5 in 10), and feeling generally unwell (about 4 in 10) [4]. Fever is less common, affecting about 1 in 15 to 1 in 20 adults [3, 4]. These reactions typically last a day or two.
The evidence on serious side effects is much weaker. The main safety studies were funded by the manufacturers and compared Tdap to a different tetanus-diphtheria (Td) vaccine, not to a true placebo or unvaccinated group [3]. That design cannot detect harms that Tdap and Td share. A large surveillance system (VSD) found no link between Tdap and several rare neurological conditions, but that system compares vaccinated people to other vaccinated people, not to the unvaccinated [2]. Passive reporting systems like VAERS catch only a tiny fraction of real adverse events [1]. One study of healthcare workers found that women and people vaccinated less than 5 years after a prior tetanus shot were about 3 times more likely to have local reactions [14]. A single case report linked Tdap to a skin condition called lichen planus [20].
| Side effect | How common it is in adults |
|---|---|
| Injection-site pain | About 75-88 in 100 [3, 4] |
| Muscle aches | About 61 in 100 [4] |
| Headache | About 53 in 100 [4] |
| Malaise | About 38 in 100 [4] |
| Fever | About 5-7 in 100 [3, 4] |
| Any side effect | About 81 in 100 [14] |
My call: Tdap predictably causes common, short-lived local and systemic reactions in most adults. The evidence for rare serious harms is too weak to rule them out, because the most informative study design (vaccinated vs. truly unvaccinated) was never run. Confidence: moderate for common side effects, low for the absence of rare serious harms.
Sources used 6
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Adverse events after Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular Pertussis (Tdap) Vaccine administered to adults 65 years of age and older reported to the Vaccine Adverse Event Reporting System (VAERS), 2005–2010
This study reviews adverse event reports following the off-label administration of the Tdap vaccine to adults aged 65 years and older, utilizing data from the Vaccine Adverse Event Reporting System (VAERS) from 2005 to 2010, and finds no significant safety concerns warranting fu…
DOI: 10.1016/j.vaccine.2011.05.100 -
Additional Recommendations for Use of Tetanus Toxoid, Reduced-Content Diphtheria Toxoid, and Acellular Pertussis Vaccine (Tdap)
Tdap can be given without a minimum interval after tetanus/diphtheria vaccines; Tdap is safe across age groups and broadly recommended, including undervaccinated children (7–10 years), health care personnel, and older adults.
DOI: 10.1542/peds.2011-1752 -
Prevention of Pertussis Among Adolescents: Recommendations for Use of Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis (Tdap) Vaccine
Adolescents should receive a single-dose Tdap booster (Boostrix or Adacel) instead of Td at the 11- to 12-year visit to provide protection against pertussis.
DOI: 10.1542/peds.2005-3038 -
Tolerability and antibody response in adolescents and adults revaccinated with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine adsorbed (Tdap) 4–5 years after a previous dose
This study evaluates the tolerability and immunogenicity of a second dose of Tdap vaccine in adolescents and adults administered 4-5 years after the initial dose, finding it to be well tolerated and immunogenic.
DOI: 10.1016/j.vaccine.2011.07.068 -
Adverse Events After Administration of Tetanus-Diphtheria-Acellular Pertussis Vaccine to Healthcare Workers
In a prospective cohort of 207 healthcare workers who received Tdap vaccine, 81% reported at least one adverse event; local adverse events were independently associated with female sex and receipt of Tdap <5 years after prior Td vaccine, and systemic adverse events were independ…
DOI: 10.1086/596201 -
Lichen planus following tetanus–diphtheria–acellular pertussis vaccination: A case report and review of the literature
This case report describes lichen planus temporally associated with tetanus-diphtheria-acellular pertussis (Tdap) vaccination in a hepatitis C virus–infected man, including clinicopathologic confirmation and a literature review on vaccine-related lichen planus and potential syne…
DOI: 10.1177/2050313X17750335