Who Is at Risk for Haemophilus influenzae Disease

Anyone can get Haemophilus influenzae disease, but some people are more likely to. Risk depends on age, race and ethnicity, vaccination, contact with someone who is sick, and medical conditions. A health care provider can answer questions about an individual's risk.

Age

Serious H. influenzae disease, including Hib disease, occurs mostly in children younger than 5 and adults 65 and older. Babies under 1 year old have the highest rates of infection.

Race and ethnicity

For reasons experts do not understand, children in some racial and ethnic groups have higher rates of serious disease:

• African American or Black children
• Alaska Native children
• American Indian children

Vaccination

Vaccines protect against one type of the disease, H. influenzae type b, or Hib. Children who have not received all their Hib vaccines, whether they missed doses or are too young to have had them all, are at higher risk of Hib disease.

Close contact

People who live with someone who has Hib disease, or go to the same child care, are more likely to be infected. Experts are working to learn whether the same is true of other types of H. influenzae infection.

Medical conditions

• sickle cell disease
• asplenia (having no spleen)
• HIV infection
• antibody and complement deficiency syndromes, rare conditions that weaken the body's ability to fight infection
• cancer that needs certain treatments: chemotherapy, radiation therapy, or a bone marrow (stem cell) transplant

Sources

• Centers for Disease Control and Prevention, "Risk Factors for Haemophilus influenzae Disease." https://www.cdc.gov/hi-disease/risk-factors/index.html
• CDC, "Haemophilus influenzae type b Vaccination": https://www.cdc.gov/hi-disease/vaccines/index.html