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Immunizations: Haemophilus Influenzae

Haemophilus influenzae disease is any type of infection caused by Haemophilus influenzae bacteria. Some of the serious infections include:

  • Pneumonia (inflamed lungs).
  • Sepsis (infection in the bloodstream).
  • Meningitis (inflamed tissue that covers the brain and spinal cord).
  • Epiglottitis (inflamed and swollen cartilage that covers the windpipe).

Haemophilus influenzae bacteria.


H. influenzae also is a common cause of ear infections in children and bronchitis in adults.

There are many different serotypes, or types, of H. influenzae. One common strain is H. influenzae type b (Hib). The Hib virus usually affects young children. Older people and people with weakened immune systems also are at higher risk of getting sick.

Despite the name, H. influenzae doesn’t cause influenza (the flu).

A vaccine can prevent Haemophilus influenzae

The best way to prevent H. influenzae is to get the vaccine.

Learn more about the Hib vaccine

Haemophilus influenzae 101

People who aren’t sick but have the bacteria in their noses and throats can spread the bacteria. That’s how H. influenzae spreads most of the time. Small respiratory droplets contain the bacteria. Other people can get sick if they breathe in those droplets.

People spread the bacteria by:

  • Coughing.
  • Sneezing.
  • Having close or lengthy contact with another person.

Hib infections are treated with antibiotics. Depending on how serious the infection is, people with H. influenzae disease may need care in a hospital.

A vaccine can prevent H. influenzae infections from the type b strain. Before the Hib vaccine was developed, the b strain of H. influenzae was the most common cause of life-threatening infections in children younger than 5 years old.

The Hib vaccine can’t protect you against other types of H. influenzae infections. Since the Hib vaccine became available in 1988, Hib cases have declined by 99 percent in infants and young children.

The Centers for Disease Control and Prevention (CDC) recommends Hib vaccines for:

Children younger than 5 years old need three or four doses of the vaccine for best protection. The number of doses needed depends on the type of vaccine brand. If a child doesn’t get the full Hib series by 5 years old, they don’t need additional doses at an older age, unless they have certain medical conditions.

Find out if you and your children got the vaccine to protect against the Hib virus. Check our Department of Health Services (DHS) Wisconsin Immunization Registry.

If you’re worried about cost, your family may be eligible for free vaccines. Read about our Vaccines For Children and Vaccines For Adults programs.

Just for health care providers

H. influenzae is a communicable disease. Health care providers must report cases of H. influenzae.

H. influenzae is a Wisconsin Disease Surveillance Category I disease

Report it right away to the patient’s local public health department. Call as soon as you identify a confirmed or suspected case. The health department then notifies the state epidemiologist.

Within 24 hours, submit a case report through one of the following:

Read more about required disease reporting in Wisconsin.

Case reporting and public health guidelines

Contact us

Last revised January 3, 2023