H. influenzae Type B : Hib Vaccine

H. influenzae Type B – Despite its name, the bacterium known as Haemophilus influenzae type b, or Hib, doesn’t actually cause the flu. Instead, it triggers Hib disease, a severe health concern for young children, especially those under 5 years old. Thankfully, since 1992, the Hib vaccine has been available, offering safe and efficient protection against this threat.

Understanding Hib Disease:

Hib disease is a dangerous bacterial infection that used to be the primary cause of bacterial meningitis in young kids. When we say it’s invasive, it means the bacteria spread to areas of the body that are typically free of germs. Meningitis involves an infection in the membrane covering the brain and spinal cord. It’s a severe condition that can lead to fever, cognitive decline, coma, and even death. Sadly, it claims the lives of 3% to 6% of affected children. Even for those who survive, many are left with severe nerve and brain damage, ranging from blindness to paralysis to intellectual disabilities.

Besides meningitis, Hib can also lead to pneumonia, epiglottitis (an infection in the throat causing breathing problems), bloodstream infections, bone infections, and joint infections resulting in arthritis.

The Hib bacteria spread through droplets released when someone sneezes or coughs. Before the vaccine, there were roughly 20,000 cases of Hib disease annually in children under 5, including 12,000 cases of meningitis, resulting in about 1,000 deaths per year.

What Causes H. influenzae Type B

Haemophilus influenzae comprises a group of bacteria responsible for various infections and illnesses. There are six main types: a, b, c, d, e, and f.

These bacteria normally reside in your throat and nose without causing any trouble. However, when they migrate to other parts of your body, they can trigger infections.

Hib, specifically type b, accounts for 95% of all severe infections. It spreads from person to person through coughs and sneezes, with the bacteria carried in droplets. Inhaling these droplets can lead to illness.

Moreover, prolonged proximity to someone carrying Hib in their throat or nose, even if they’re asymptomatic, can result in transmission.

Fortunately, experts believe that Hib cannot survive on surfaces devoid of life, which is reassuring.

Who’s at Risk for H. influenzae Type B

Children under 5 years old face the highest risk of Hib infection. Additionally, adults aged 65 and above, along with individuals with weakened immune systems, are also susceptible. Certain groups with specific characteristics are at an increased likelihood of contracting Hib, including:

• American Indian and Alaska Native populations
• Individuals with:
• Asplenia (absence of a spleen)
• HIV infection
• Sickle cell disease
• Antibody and complement deficiency syndromes (rare conditions affecting the body’s ability to fight infections)
• Cancer necessitating chemotherapy, radiation therapy, or bone marrow stem cell transplant.

What Are the Symptoms of H. influenzae Type B

The symptoms of Hib infection vary depending on the disease it causes. Here’s what you might experience:

1. Ear Infection: Symptoms include loss of appetite, pain, irritability, disrupted sleep, fever, drainage from the ear, or difficulty hearing.
2. Cellulitis: This bacterial skin infection can lead to tenderness, pain, swelling, warmth, blisters, skin discoloration, fever, chills, or fatigue.
3. Bronchitis: You may experience a cough with mucus, wheezing, fever, fatigue, and shortness of breath.
4. Pneumonia: Symptoms may include fever, chills, cough, shortness of breath, sweating, difficulty breathing, chest pain, headache, muscle pain, or fatigue.
5. Meningitis: Signs of meningitis include fever, headache, fatigue, stiff neck, loss of appetite, nausea, vomiting, confusion, irritability, or seizures.
6. Epiglottitis: This condition makes swallowing difficult and can cause a sore throat, fever, raspy breathing, drooling, or difficulty breathing.
7. Septicemia (Bloodstream Infection): Symptoms might include abdominal pain, fever, chills, nausea, vomiting, diarrhea, confusion, anxiety, fatigue, shortness of breath, or difficulty breathing.
8. Septic Arthritis: You may notice joint pain, warmth, fever, tenderness, swelling, and limited range of motion.

How Do Doctors Diagnose Hib?

To diagnose Hib, doctors typically perform one or more laboratory tests. These may involve collecting samples of:

• Blood
• Joint fluid
• Spinal fluid
• Pleural fluid (fluid around the lungs)
• Middle ear aspirate

Initially, they use a test called Gram staining to detect bacteria in the samples. This helps identify the type of bacteria causing the illness. To confirm a Hib diagnosis, your doctor may conduct a blood culture or culture of other body fluids.

How Long Is Hib Contagious?

Doctors don’t have exact information on the incubation period for Hib. However, they believe that symptoms may develop within a few days after infection.

Treatment for Hib:

Typically, doctors prescribe antibiotics to combat the infection. In severe cases, hospitalization may be necessary for additional treatments, such as:

• Intravenous (IV) steroids
• Breathing support using oxygen masks or intubation
• Medications to manage low blood pressure
• Wound care, if applicable
• Surgical drainage for septic arthritis

Can the Hib Vaccine Cause Hib Disease?

No, it cannot. The Hib vaccine is derived from a coating of the Hib bacteria, combined with a protein. This combination stimulates the body’s immune response to build immunity against Hib. Since only the bacterial coating is used, it cannot cause Hib infection or disease.

Is the Hib Vaccine Safe and Compatible with Other Vaccines?

Yes, the vaccine is safe. Common side effects may include soreness, swelling, or redness at the injection site, and severe allergic reactions are rare. It can be administered alongside other vaccines or as part of a combination vaccine. Typically, the Hib vaccine is included in a child’s regular vaccination schedule.

Who Should Get the Vaccine?

The CDC recommends that children under the age of 5 receive the Hib vaccine. Ideally, the first dose should be administered at 2 months of age.

While Hib disease is rare in older children and most adults have built antibodies against Hib, the vaccine is recommended for those aged 5 and above only if they’re at increased risk of Hib infection. This includes individuals who:

• Have had their spleen removed
• Have sickle cell disease, leukemia, or HIV
• Have a weakened immune system due to illness or treatment, such as cancer treatment.

How Many Doses of the Hib Vaccine Are Needed?

Various Hib vaccines are licensed for use in the U.S., all equally effective. The number of doses required for full immunity—either three or four—depends on the specific vaccine used. For adults and older children at increased risk who haven’t been vaccinated before, at least one dose is necessary for protection.

When Should My Child Be Vaccinated?

According to the CDC, infants should receive the first dose at 2 months, the second dose at 4 months, and the third dose (depending on the vaccine) at 6 months. A booster shot is recommended between 12 and 15 months of age.

Children under 6 weeks should not receive the vaccine, as it may cause a reaction that hinders their response to later doses. Most newborns possess natural immunity to Hib passed down from their mothers, which eventually diminishes.

What Happens if My Child Misses a Dose?

If your child misses a dose, they can receive a catch-up shot at their next doctor’s visit without needing to restart the series.

Can a Child Still Get Meningitis After Vaccination?

While the Hib vaccine protects against Hib meningitis, other germs can still cause meningitis. However, the risk is significantly lower with vaccination compared to without it.

Sources

Pediatrics, published online Feb. 1, 2011.

Immunization Action Coalition: “Hib Vaccine Questions and Answers.”

The Children’s Hospital of Philadelphia Vaccine Information Center: “A Look at Each Vaccine: Hib Vaccine.”

CDC: “Is Your Baby Protected against Hib Disease,” “Causes, How it Spreads, & People at Increased Risk.”

Cleveland Clinic: “Haemophilus Influenzae.”