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Haemophilus Influenzae Type B (Hib) Information for the Public
Hib disease is caused by a bacterium Haemophilus influenzae type b.
Haemophilus influenzae can cause many types of infections. Some of these infections are mild, while others are serious.
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Transmission (Spread)
People spread H. influenzae to others by coughing or sneezing, which creates small respiratory droplets that contain the bacteria. Other people can get infected if they breathe in those droplets.
People who aren't sick but have the bacteria in their nose and throat can still spread the bacteria.
The bacteria can also spread to people who have close or lengthy contact with an infected person.
About Haemophilus influenzae Disease (Centers for Disease Control and Prevention)
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Prevention
Vaccines can prevent Hib disease, but not disease caused by other types of H. influenzae. The best way to prevent Hib disease is to get vaccinated.
CDC recommends Hib vaccines for all children younger than 5 years old.
The routine schedule for Hib vaccination in children is:
- Dose 1: 2 months
- Dose 2: 4 months
- Dose 3: 6 months (if needed; depends on brand)
- Dose 4: 12 through 15 months
People can get H. influenzae, including Hib, disease more than once. Maintaining healthy habits, like washing hands often and not having close contact with people who are sick, helps prevent H. influenzae disease.
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Signs and Symptoms
Symptoms of pneumonia, a serious lung infection, include:
- Fever, chills, or sweating
- Cough
- Shortness of breath or difficulty breathing
- Chest pain
- Headache
- Muscle pain or aches
- Excessive tiredness
- Fever and chills
- Excessive tiredness
- Pain in the belly
- Diarrhea or nausea with or without vomiting
- Anxiety
- Shortness of breath or difficulty breathing
- Altered mental status (confusion)
Symptoms of bloodstream infection include:
Symptoms of meningitis include sudden onset of:
- Fever
- Headache
- neck
- Nausea with or without vomiting
- Photophobia (eyes being more sensitive to light)
- Altered mental status (confusion)
Babies with meningitis may:
- Be irritable
- Vomit
- Feed poorly
- Appear to be slow or inactive
- Have abnormal reflexes
Hib disease can also cause mild infections including:
- Ear infections
- Bronchitis Serious infections can result in long-term health problems including brain damage, limb loss, and death.
Serious infections can result in long-term health problems including brain damage, limb loss, and death.
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Risk of Disease
- Before vaccination, Hib was one of the leading causes of bacterial meningitis.
- Before vaccination, there were 20,000 cases each year in the U.S.
- Vaccination has reduced Hib infections by 99%.
- 3% to 6% of Hib cases in children are fatal, higher in adults over age 65.
- Up to 20% of patients who survive Hib meningitis have permanent hearing loss or other long-term neurological effects.
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Reporting
H. influenzae is a notifiable disease. A notifiable disease is one that doctors must report to state or local public health officials.
Public health officials track some diseases because they can spread easily, are serious, or happen often.
Notifiable diseases in Michigan:
Michigan's List of Notifiable Diseases 2025 By Condition
Michigan's List of Notifiable Diseases 2025 By Pathogen -
Questions About
Get answers to frequently asked questions about Haemophilus influenzae type b (Hib) and the vaccine used to prevent it.
Haemophilus influenzae type b (Hib): Questions and Answers (immunize.org)
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For More Information
Hib Vaccination
Haemophilus Influenzae Type b (Hib): The Disease & Vaccines | (Children's Hospital of Philadelphia)
How Vaccines Work
Video: How Do Vaccines Work? (American Academy of Pediatrics)
- Spanish version: ¿Cómo funcionan las vacunas? (American Academy of Pediatrics)
- Spanish version: ¿Cómo funcionan las vacunas? (American Academy of Pediatrics)
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Access Your Immunization Record
If you have been immunized in the State of Michigan, you may be able to download your immunization record from the Michigan Care Improvement Registry (MCIR).
Visit the Michigan Immunization Portal to learn more or contact your healthcare provider.