Diphtheria Vaccine

What Is Diphtheria?

Diphtheria is a highly contagious and potentially life-threatening infection 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. But, in more serious cases, it may affect the nervous system and heart.

Diphtheria spreads easily from person to person by coughing or sneezing from infected persons. People nearby breathe in the infected water droplets or, on rare occasions, come into direct contact with excretions from an infected person’s mouth, nose, throat, or skin, where bacteria reside.

Because of a widespread immunization program beginning in the 1930s, diphtheria is now rare in the United States. Between 1980-1995, only 41 cases of diphtheria were reported to US health authorities. However, diphtheria is still prevalent in some areas of the world where people live in crowded, unsanitary conditions where immunization practices are sporadic. In 1993 and 1994, more than 50,000 cases were reported during a serious outbreak of diphtheria in countries of the former Soviet Union.

Symptoms of diphtheria usually begin 2-4 days following exposure. A doctor will confirm the diagnosis through an examination and throat culture.

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, which 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, immediate hospitalization and treatment upon diagnosis is essential.

Treatment primarily consists of a specially-derived diphtheria antitoxin given through injection and antibiotics. Some patients may also need a respirator to help them breath. After the antitoxin and antibiotics have taken effect, diphtheria patients will need bed rest for approximately 4-6 weeks, depending on the severity of the case. They should also continue to receive the diphtheria boosters because contracting the disease doesn't guarantee immunity for life.

What Is the Diphtheria Vaccine?

The diphtheria vaccine is an inactivated toxin called a toxoid. It is cultivated by growing the bacteria in a liquid climate where the toxin is then purified and inactivated.

Although it is available as a single vaccine, it is normally given in combination with the tetanus and pertussis (better known as whooping cough) vaccines, together known as the DTaP vaccine (for children) and Tdap (for adolescents and adults). In children who cannot receive the pertussis component of the DTaP vaccine because of an allergic or other adverse reaction, the inoculation may be given in combination with tetanus alone, known as the DT vaccine.

The vaccine is usually given as an injection into the muscle.

Who Should Get Vaccinated and When?

All children (with few exceptions) should receive the diphtheria vaccine, usually in the form of the DTaP shot. The regular immunization 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 vaccination, the Centers for Disease Control and Prevention (CDC) recommend the following catch-up schedule:

Children seven years and older and adults who have not been vaccinated should also be vaccinated. The choice and timing of vaccination will vary based on age and prior vaccine exposure. The main difference between the childhood and adult vaccines is that the pediatric version contains 3-5 times the amount of diphtheria toxoid as the adult version.*

The rate of effectiveness of the vaccine is approximately 95%. This means that 95% of those receiving the vaccine are adequately protected against the infection after being immunized as recommended.

What Are the Risks Associated With the Diphtheria Vaccine?

Most people tolerate it well, but the diphtheria vaccine sometimes causes mild side effects such as soreness or redness at the site of the injection, a low-grade fever, fatigue, general irritability, lack of appetite, and vomiting. More serious complications such as allergic reactions, crying for over three hours, and high fever are rare. Seizures associated with brain damage are extremely rare.

Who Should Not Get Vaccinated?

It is the rare child that cannot safely receive the diphtheria vaccine. There are two circumstances where the risks of the vaccine outweigh its benefits: severe allergic reaction (anaphylaxis) or severe brain disorder (encephalitis) occurring within 7 days of vaccination and having no other explanation.

Since the diphtheria vaccine is almost always given in combination with tetanus and pertussis (as DTaP), it can be difficult to sort out which component led to these adverse effects. Therefore, under the circumstances, it is usually safest to avoid all three vaccines, although many children who recover from encephalitis or other serious adverse reactions (see below) may eventually be able to receive a diphtheria-tetanus (DT) vaccine without incident. Children who develop any of the following serious reactions soon after the vaccine should see their physician about the safety of receiving future vaccinations:

• 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

Children with moderate to severe acute illnesses at the time of their scheduled immunization should postpone vaccination until the illness has resolved. However, children with mild respiratory illness, or who develop low-grade fever or local soreness or redness after a DTaP vaccine, should receive the vaccine on schedule.

What Other Ways Can Diphtheria Be Prevented Besides Vaccination?

Preventing diphtheria depends completely on immunization and prompt response to outbreaks.

What Happens in the Event of an Outbreak?

It is essential for every suspected case of diphtheria to be promptly reported, so public health authorities can quickly determine if an outbreak has taken place. Once your doctor has diagnosed a case of diphtheria, he or she will report it to the authorities.

In the event of a suspected or confirmed diphtheria outbreak, only close contacts are considered to be at risk (for example, household members and others potentially exposed to secretions of the confirmed or suspected case.) Close contacts who have received fewer than three doses of the vaccine series should have an immediate dose and then complete the series as scheduled. Close contacts who have completed their initial series, but have not had a dose in the previous five years, should receive a booster dose. Furthermore, all close contacts regardless of their diphtheria immunization status should have samples taken for culture, promptly receive antibiotics, and be followed closely for at least seven days for evidence of infection.