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Disease information

Virus or bacteria

Hib is caused by the bacterium, Haemophilus influenzae type b.

How it spreads

• Coughing
• Sneezing

While anyone can get Hib, infections often occur in children less than 4 years of age. If 10 susceptible children (less than 4 years of age) are exposed to a person infected with Hib, up to 1 of 10 children will become infected.

Symptoms

Symptoms will vary based on the complication that occurs.

Typical disease timeline

The length of illness for this disease varies, depending on a number of factors, including which disease complications occur. The image shown indicates the likelihood of experiencing a particular complication.

Possible complications

• Meningitis (4 of 100 people with Hib meningitis will die.)
• Sepsis
• Arthritis
• Osteomyelitis
• Pericarditis
• Pneumonia
• Epiglottitis
• Otitis media

Other things to know

• Haemophilius influenzae type b (Hib) was the most common cause of meningitis in children less than 5 years old before introduction of the vaccine.
• Before the vaccine, Hib was commonly found on the surface of the nose and back of the throat. Although most people were not sick, they could still transmit the bacteria to others. Each year, about 20,000 children would get serious infections with Hib, and some would die.
• Antibodies against Hib pass to a baby before birth through the placenta. However, these antibodies are short-lived, so protection decreases during the first 6 months of life making babies increasingly susceptible to Hib infections. For this reason, children should be fully immunized by the time they are 6 months old, so they can be protected by their own immune system.
• Haemophilus influenzae type b only infects people.

Vaccine information

The Hib vaccine is used to prevent Haemophilus influenzae type b (Hib). 

Vaccine type

• Polysaccharide vaccines

Vaccine side effects

Common

• Pain or soreness at the injection site (5 to 30 of 100 recipients)
• Low-grade fever (11 to 26 of 100 recipients)
• Loss of appetite (About 20 of 100 recipients)
• Irritability (62 to 71 of 100 recipients)

Rare

• None

Very rare

• Serious allergic reaction (fewer than 1 of 1,000,000 recipients)

Other things to know

The Hib vaccine does not prevent all causes of meningitis. Other bacteria and some viruses can also cause meningitis:

• Bacterial meningitis can be caused by pneumococcus and meningococcus.
• Viral meningitis can be caused by mumps, chickenpox and enteroviruses.

Viral meningitis is often less severe than bacterial meningitis.

Reasons to get the Haemophilus influenzae type b (Hib) vaccine

• Hib still exists.
• Infants and young children are the most susceptible to Hib.
• Unvaccinated and partially vaccinated children are at higher risk of disease caused by Hib.
• The Hib vaccine decreases the number of Hib carriers in the population.
• The Hib vaccine is safe.