Hib disease is a serious illness caused by the bacteria Haemophilus influenzae type b. Babies and children younger than 5 years old are most at risk for Hib disease. It can cause lifelong disability and be deadly. The Hib vaccine prevents Hib disease.
In-depth information from the Centers for Disease Control and Prevention (CDC)
Fact sheet from Centers for Disease Control and Prevention (CDC), American Academy of Family Physicians (AAFP), and American Academy of Pediatrics (AAP)