Diphtheria, tetanus, and pertussis (whooping cough) are three contagious diseases that can cause life-threatening symptoms. To help prevent these conditions in children as well as adolescents and adults, there are various vaccines. The vaccine that is most often administered to protect against these three conditions in children is the DTaP vaccine, but there are also other combination products available for each of these three ailments.
Let’s look at each of the three diseases separately and then discuss the vaccines available to help prevent them.
Diptheria
The bacterium Corynebacterium diphtheria is the culprit in this disease. The microorganism releases a toxin that is responsible for the symptoms, which can include croup-like cough, wheezing, rapid breathing, watery or bloody discharge from the nose, severe sore throat, fever, painful swallowing, drooling, bluish skin, and chills. Because the toxin travels throughout the bloodstream, it can have a detrimental impact on any of the organs.
Diphtheria can be life-threatening, and treatment should begin immediately. Options include antibiotics such as erythromycin or penicillin, and children typically need to be hospitalized. Ten percent of children who develop diphtheria die of the disease. The most common complication is myocarditis (inflammation of the heart muscle) as well as nervous system damage that may cause temporary paralysis.
Tetanus
Tetanus, also known as lockjaw, is caused by a toxin released by the bacterium called Clostridiuim tetani. Fortunately, tetanus is rarely seen in the United States, with only about 40 to 60 cases per year.
When cases do occur, the individuals experience muscle contractions that can be so severe, a person’s bones can break. Other symptoms can include breathing difficulties, sweating, elevated blood pressure, rapid heart rate, damage to the heart muscle, and fever.
Women who are pregnant or who plan to become pregnant and who are not sure when they had their last tetanus shot should see their doctor and be immunized, according to the Centers for Disease Control and Prevention (CDC). Women who are immunized pass along tetanus antibodies to their infant through the placenta.
Read more about Hib and polio vaccines
Pertussis
Of these three diseases, pertussis is the one that has been a significant treatment challenge in the United States. Even though every state requires that all children be vaccinated against these diseases before they enter school, thousands of cases of pertussis are reported annually. In fact, as of June 16, 2014, nearly 10,000 cases of pertussis had been reported in the United States so far this year, which represents a 24 percent increase over the same time in 2013.
Pertussis is caused by the bacterium Bordetella pertussis or B. parapertussis. The initial symptoms are similar to those of the common cold, but after about 10 to 12 days, the characteristic “whooping” sound at the end of a cough occurs along with difficulty breathing. Other symptoms can include fever, runny nose, diarrhea, vomiting, and loss of consciousness. Pertussis is especially dangerous in infants and young children, who may also develop pneumonia, nose bleeds, ear infections, convulsions, brain damage, mental retardation, bleeding in the brain, or death.
Vaccines for Diphtheria, Tetanus, and Pertussis
Diphtheria, tetanus, and pertussis are often but not always treated together in one combination vaccine. The four combination vaccines used to prevent diphtheria, tetanus, and pertussis include:
- DTaP: This is the most commonly administered vaccine and is for children younger than 7 years of age
- DT: This vaccine does not contain pertussis and is used as a substitute for kids who cannot tolerate pertussis vaccine
- Td: This combination of tetanus and diphtheria vaccine is for adolescents and adults as a booster shot every 10 years.
- Tdap: This vaccine is similar to Td, but it also protects against pertussis. Tdap is for adolescents ages 11 to 18 (but preferably given at age 11 to 12), adults ages 19 through 64 years, older adults (65 and older) who have close contact with an infant and who have not previously received Tdap, and children ages 7 to 10 who are not fully immunized against pertussis.
Here’s what the letters in the vaccines mean:
- Upper-case letters refer to full-strength doses (e.g., D, T, P)
- Lower-case letters indicate reduced doses used in adolescent and adult vaccines
- “a” is short for “acellular,” which means the pertussis portion of the vaccine contains only a small portion of the pertussis organism
The DTaP vaccine is 95 percent effective in preventing these three conditions. However, the tetanus portion of the vaccine lasts only a decade, so the CDC recommends everyone receive a booster shot (Td) every 10 years. The three currently available DTaP vaccines are Daptacel, Infanrix, and Tripedia. All three contain inactivated bacterial vaccines, the same three microorganisms (Bordetella pertussis, Corynebacterium diphtheria, Clostridium tetani), and are given via intramuscular injection. In addition, there are two other combo vaccines: Kinrix, which contains a polio vaccine along with the other three; and Pediatrix, which is designed for the four diseases in Kinrix plus hepatitis B. Yet another vaccine is called Boostrix, which is for any child who is 10 years or older and who has not been immunized for diphtheria, tetanus, or pertussis.
Daptacel: Contains aluminum phosphate, formaldehyde, glutaraldehyde, ammonium sulfate, and formalin. The preservative is 2-phenoxyethanol.
Infanrix: Ingredients include aluminum hydroxide, formaldehyde, polysorbate 80, sodium chloride, and glutaraldehyde. Infanrix does not
contain preservatives.
Tripedia: This vaccine contains aluminum potassium sulfate, formaldehyde, gelatin, polysorbate 80, and ammonium sulfate. The preservative thimerosal is present.
Boostrix: This Tdap vaccine contains aluminum hydroxide, formaldehyde, polysorbate 80, sodium chloride, and glutaraldehyde, but no preservatives.
Kinrix: The diphtheria, tetanus, and pertussis components are the same as those in Infanrix and Pediarix, and the poliovirus component is the same as the one in Pediarix. Kinrix contains luminum hydroxide, sodium chloride, formadldehyde, polysorbate 80, neomycin, and polymyxin B, but no preservatives.
Pediarix: The diphtheria, tetanus, and pertussis components in this vaccine are the same as those in Infanrix, and the hepatitis B antigen is the same as that in Engerix-B. It also contains the antigens for the three types of poliovirus. Ingredients in Pediarix include aluminum salts, sodium chloride, formaldehyde, polysorbate 80, neomycin sulfate, polymyxin B, and yeast protein.
Read more about hepatitis B vaccines
To make the diphtheria vaccine, the toxin that is released by the bacteria is inactivated with a chemical. When this inactivated toxin (toxoid) is injected into the body, it causes an immune response to the toxin but does not cause the disease. The tetanus vaccine works in a similar way, but the pertussis vaccine has a different mechanism of action.
Because the bacteria that cause pertussis make several different toxins, vaccine producers have chosen a few toxins and inactivate them with a chemical. The currently available pertussis vaccine is an acellular vaccine and is associated with significantly fewer side effects than the earlier, wholecell vaccine.
Vaccination Schedule for DTaP
All 50 states and the District of Columbia require children to be vaccinated against diphtheria, tetanus, and pertussis before they enter school. Here is the recommended vaccination schedule:
- Five injections are given at ages 2, 4, 6, 15 to 18 months, and at 4 to 6 years of age. If the fourth dose is given after a child is four years old, no fifth dose is necessary.
- Children younger than age seven who cannot get the pertussis vaccine should be given the DT vaccine. Then the Td vaccine should be administered between the ages of 7 and 9 years.
- The Tdap vaccine should be given as a booster shot to kids who are age 11 to 12 years (and no later than age 16 years).
Some young people should not be given some or all of the vaccines for diphtheria, tetanus, and pertussis. For example:
- Anyone who has a history of a serious allergic reaction to any of the vaccines’ components
- Children ages 7 to 9 years of age should not receive any vaccine that contains pertussis components
- Any child who has symptoms of a moderate to severe illness should postpone getting the vaccine. In addition, children who have experienced reactions after receiving a previous DTaP injection, who have had seizures or who have a sibling or parent who has seizures, or who has a brain condition that is worsening or not responding to treatment should talk to their doctor before allowing vaccination to occur.
Side Effects
The DTaP vaccine may cause crankiness, decreased appetite, fever, soreness at the injection site, and vomiting that may last several days. More specifically, clinical trials indicate that the DTaP vaccine can cause the following adverse effects:
- Pain, redness, and swelling at the injection site, with the symptoms being greatest after doses 4 and 5: 10% to 53% of patients.
- Fever following doses 1, 2, and 3: 20% to 30%
- Drowsiness, irritability/fussiness, loss of appetite: 15% to 60% based on the dose and circumstances
On rare occasions, nonstop crying for more than three hours (occurs in 1 in 1,000 children), fever higher than 105 degrees (1 in 16,000 children), or seizures (1 in 14,000 children) can occur. Severe reactions to the DTaP vaccine (less than 1 per 1,000,000 children) include breathing problems, low blood pressure, and shock.
The bottom line
You are encouraged to explore the pros and cons of DTaP and other vaccines for your child before making a decision about if and when to have them administered. Talk to your healthcare provider about alternative scheduling of your child’s vaccines as well. Exemptions for children’s vaccines are available in all 50 states and the District of Columbia.
Deborah Mitchell is the author of The Essential Guide to Children's Vaccines 
Image: US Army Corps of Engineers
