Although aims of the two combination vaccines are the same, their composition and indications for use differ.

Tdap or Td (tetanus and diphtheria vaccine) is recommended as a booster every 10 years to sustain immunity to these potentially serious infectious diseases.

Uses

The Tdap vaccine was licensed for use in adults and adolescents by the U.S. Food and Drug Administration (FDA) on June 10, 2005.

It is used to afford ongoing protection against three diseases:

Tetanus: This relatively rare but serious disease is caused by a bacteria that enters the body through breaks in the skin. Commonly known as lockjaw, tetanus causes a painful tightening of the muscles (including the mouth, jaw, abdomen, and neck) as well as fever, difficulty swallowing, fever, and rapid heart rate. If left untreated, tetanus can be fatal in up to 20% of cases. Diphtheria: Also caused by a bacteria, diphtheria manifests with a thick coating on the back of the throat. If left untreated, it can lead to breathing difficulty, swallowing problems, and heart failure. In extreme cases, paralysis and even death can occur. Pertussis: Also known as whooping cough, this bacterial infection causes a distinctive cough that literally sounds like whoop. The severe coughing spells can cause vomiting and sleep disturbances. Untreated, pertussis can lead to weight loss, rib fractures, pneumonia, and hospitalization.

Indications for Use

The Centers for Disease Control and Prevention (CDC) recommends diphtheria, tetanus, and pertussis (whooping cough) vaccination for everyone.

While the DTaP vaccine is given as a series of five shots to children from 2 months through 6 years, the Tdap vaccine is indicated for anyone 10 years or older as a booster shot to sustain immunity.

There are two Tdap vaccine licensed for use by the FDA:

Adacel: Approved for people 10 to 64 years of ageBoostrix: Approved for people 10 years of age or older

When used as a booster, Tdap is typically given five years after the completion of the DTaP series and then every 10 years thereafter.

Other Uses

Though the Tdap vaccine is primarily used as a booster shot for people who have been previously immunized against tetanus, diphtheria, and pertussis, it has other uses as well.

Among the other indications for use are:

Previously unvaccinated people: Healthcare providers can give Adacel or Boostrix to anyone 7 years and older who has not been previously vaccinated for diphtheria, tetanus, and pertussis. Pregnancy: Adacel or Boostrix is also given during pregnancy to protect a woman’s baby from whooping cough during the first months of life. Wound management: To prevent tetanus, the Tdap or Td vaccine is given to people who have a tetanus-prone wound.

Before Using

Although vaccination for tetanus, diphtheria, and pertussis is recommended for everyone, there a few rare individuals in whom Tdap vaccination may be harmful.

Neither Adacel nor Boostrix should ever be used in:

Anyone who has had a life-threatening allergic reaction to a dose of the Tdap vaccine or to any other diphtheria, tetanus, or pertussis vaccine Anyone with a severe allergy to any component of Tdap

Be sure to advise your healthcare provider if you or your child has epilepsy or any other neurological condition. The same applies if you or your child has ever had a severe autoimmune disorder called Guillain-Barré syndrome (GBS).

However, in neither instance is the Tdap vaccine contraindicated, and the chances of a severe reaction are rare. Of note, a 2013 study in Clinical Infectious Diseases could find no evidence of an increased risk of GBS following vaccination of any kind.

Dosage

The administration of Adacel and Boostrix is nearly identical but there are some minor variations. Even so, some healthcare providers and clinics use them interchangeably.

Both are given as an injection into a large muscle in a 0.5 milliliter (mL) dose. The vaccine either comes in a single-use vial or as a prefilled syringe. The shot is preferentially given in the deltoid muscle of the shoulder.

Some healthcare providers and clinics will use the tetanus-diphtheria (Td) vaccine, rather than the Tdap vaccine, for routine boosters. Even so, the CDC recommends that one of the Td doses be substituted with the Tdap vaccine to protect against pertussis in adults, who are more likely to be hospitalized if infected.

Side Effects

Side effects to the Tdap vaccine, if any, tend to be mild and transient, usually resolving within a day or two. Severe side effects are rare but can occur.

Call your healthcare provider or clinic immediately if you experience any side effects that are unusual, persistent, or worsening.

Common

The most common side effects experienced by those who receive Adacel or Boostrix include:

Injection site pain, redness, or swellingHeadacheFatigueGastrointestinal symptoms (including nausea, diarrhea, stomach pain, vomiting)Fever

With Adacel, muscle pain and malaise are also common.

Severe

Severe side effects are rare with Adacel and Boostrix. The following adverse events have been noted in post-marketing surveillance, although a causal association has not been found:

Facial palsy Convulsions Encephalitis Fainting

These events are so rare that it remains unclear if the vaccines have anything to do with them.

Warnings and Interactions

Out of an abundance of caution, the Tdap vaccine is deferred in people who have a progressive or unstable neurological disorder until such time as the symptoms have stabilized.

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Tdap vaccines are sometimes given at the same time as other vaccines. Most of the time doing this is not a problem and will not undermine the efficacy of either vaccine.

The only exceptions may be the flu vaccine or, with Boostrix, the meningococcal vaccine Menactra. There is evidence, albeit scant, that using these vaccines together may reduce the antibody response against pertussis. While the interaction may be negligible, you may want to separate the doses by four weeks just in case.

On the other hand, advise your healthcare provider if you are on any immunosuppressive therapy as this can undermine the effectiveness of Tdap and other vaccines. This includes:

Chemotherapy High-dose corticosteroids (including prednisone) Radiation therapy