What Is Diphtheria?

Diphtheria is a highly contagious and potentially life-threatening infection. It is caused by a bacterium called Corynebacterium diphtheriae. The germ produces a toxin that can spread from the site of infection to other tissues in the body. Diphtheria usually affects the throat and nose. In serious cases, it may affect the nervous system and heart.

Diphtheria spreads easily from person to person by coughing or sneezing. People nearby breathe in the infected droplets. In rare cases, they come into direct contact with excretions from an infected person’s mouth, nose, throat, or skin.

Because of a widespread immunization program, diphtheria is now rare in the US.

Symptoms usually begin 2-4 days following exposure. Early symptoms include:

  • Sore throat
  • Fever
  • Swelling of the lymph nodes and surrounding tissue on both sides of the neck (known as “bullneck”)
  • Difficulty swallowing or breathing

Later symptoms may include:

  • Thick speech
  • Respiratory distress
  • Signs of shock, such as pale cold skin, rapid heartbeat, and sweating

The toxin produced by the bacterium may cause a coating to form in the nose, throat, or airway. This is what causes difficulty breathing or swallowing. In cases that spread beyond the throat, the toxin can cause damage to the heart or kidneys. It can also cause nerve damage and lead to paralysis. Since untreated cases can be fatal, people need to be hospitalized and treated right away.

Treatment consists of an antitoxin and antibiotics. Some people may also need a respirator to help them breath. Bed rest is needed for about 4-6 weeks. Diphtheria booster shots will be needed.

What Is the Diphtheria Vaccine?

The diphtheria vaccine is an inactivated toxin called a toxoid.

Although it is available as a single vaccine, it is normally given in combination with the tetanus and pertussis vaccines. Together they are known as the DTaP vaccine (for children) and Tdap (for adolescents and adults). In children who cannot have the pertussis part of the vaccine, the DT (diphtheria and tetanus) vaccine is used.

The vaccine is injected into the muscle.

Who Should Get Vaccinated and When?

All children (with few exceptions) should receive the vaccine, usually in the form of the DTaP shot. The regular schedule (for children and adults) is as follows:

  • DTaP vaccines at 2, 4, 6 months, 15-18 months, and 4-6 years of age
  • Booster dose of Tdap given at 11 or 12 years old—This is for children who have not already had the Td booster.
    • Those aged 13-18 years who missed the above booster dose or received Td only can receive one dose of Tdap 5 years after the last dose.
  • Booster of Tdap (one time dose for ages 19-64 years) or Td (every 10 years) to provide continued protection

For children aged 4 months to 6 years who have not yet received the vaccine, the Centers for Disease Control and Prevention (CDC) recommend the following catch-up schedule:

DosesMinimum Interval Between Doses
First and second dose4 weeks
Second and third dose4 weeks
Third and fourth dose6 months
Fourth and fifth dose 6 months
  • The fifth dose is not needed if the fourth dose was given at age 4 years or older.
  • DTaP is not for people aged 7 years or older.

Unvaccinated children (aged seven years and older) and adults should get the vaccine.

People who meet the following criteria should also get the vaccine:

  • Adults who expect to have close contact with an infant younger than 12 months should get a dose of Tdap (with a waiting time of two years since the last dose of Td)
  • Healthcare workers who have direct patient contact with hospitals or clinics should get a dose of Tdap (with a waiting time of two years since the last dose of Td)
  • Pregnant women:
    • If last dose of Td was 10 years ago or longer, they should get a dose of Td
    • If last dose of Td was less than 10 years ago, they should get a dose of Tdap after giving birth

What Are the Risks Associated With the Diphtheria Vaccine?

Most people tolerate it well, but the diphtheria vaccine sometimes causes:

  • Mild side effects: soreness or redness at the site of the injection, a low-grade fever, fatigue, general irritability, lack of appetite, and vomiting
  • More serious complications:
    • Rare: allergic reactions, crying for over three hours, and high fever
    • Very rare: seizures associated with brain damage

Acetaminophen (eg, Tylenol) is sometimes given to reduce pain and fever that may occur after getting a vaccine. In infants, the medicine may weaken the vaccine's effectiveness. Discuss the risks and benefits of taking acetaminophen with the doctor.

Who Should Not Get Vaccinated?

There are two circumstances where the risks of the vaccine outweigh its benefits:

Since the diphtheria vaccine is generally given as DTaP, it can be hard to determine which component is causing a problem. It is usually best to avoid all three vaccines if there are serious side effects.

If your child has any of these reactions, you should get medical care right away:

  • Fever greater than 105ºF (40.5ºC)
  • Severe swelling of the entire limb used for the vaccination
  • Collapse with shock-like state (unresponsive with low blood pressure)
  • Persistent, inconsolable crying lasting more than three hours
  • Convulsions, with or without fever, occurring within three days

If your child has a moderate to severe illness, wait until he has recovered before getting the vaccine.

What Other Ways Can Diphtheria Be Prevented Besides Vaccination?

Prevention depends on getting the vaccine and responding quickly to outbreaks.

What Happens in the Event of an Outbreak?

Suspected cases of diphtheria need to be reported right away to public health authorities.

In the event of a suspected or confirmed outbreak, only close contacts are considered to be at risk. For close contacts, treatment includes:

  • Getting a dose right away if you have had fewer than three doses
  • Getting a booster dose if you have not had a dose in five years
  • Having samples taken for lab tests, taking antibiotics, and being followed closely for seven days (even if you have been vaccinated)