Haemophilus influenzae type b (Hib) is one of several types of Haemophilus influenzae bacteria, but it is notorious for causing severe disease in young children. Though many types of Haemophilus influenzae exist and can cause illness, Hib is the only type for which a vaccine is available. Hib disease can cause young children to become very sick with meningitis (swelling of the covering of the spinal cord and brain), blood infections, pneumonia, and illness in other parts of the body. Fortunately, most children now get a vaccine for Hib disease. Before the vaccine, Hib infections were common, and many children who got Hib disease died or were permanently disabled.
Infants and children under age 5 are at higher risk for Hib disease if they have not had the Hib vaccine. American Indians and people who are Alaska Natives tend to get this disease more often than other people, so it is important to make sure children in these groups are vaccinated. Adults with weakened immune systems can sometimes be at risk for Hib disease and should ask their doctor if they need the Hib vaccine.
Hib disease usually causes high fever, pain, and feeling very tired. Children with Hib infections may act very irritable and fussy, though meningitis can also cause severe lethargy or limpness in infants. Since Hib disease can affect many parts of the body, it may cause other symptoms as well.
Diagnosis
See your doctor. Most people who were born after 1990 got the Hib vaccine when they were infants. The number of cases of Hib diseases in young children in the United States has dropped because most children are vaccinated. Many other illnesses can have the same symptoms as Hib disease, and a lab test is usually required to make a definite diagnosis of Hib disease. Sometimes, it may not be Hib, but another type of Haemophilus influenzae bacteria causing infection.
Treatment
Since all types of Haemophilus influenzae infections are caused by bacteria, they can be treated with antibiotics. People who live with a child with Hib and playmates of a child with Hib may also need to take medicine so they don’t get sick. Your doctor or local health department will be able to make appropriate recommendations for your situation.
Hib disease is spread through droplets from the nose and throat of a person who has the Hib bacteria in their nose or throat. This can happen when someone with the bacteria coughs or sneezes near someone else or when someone touches objects with nose or throat droplets of an infected person on them. People can spread Hib disease as long as they have Hib bacteria in their noses and throats, even if they seem healthy. It is unknown how long it takes from the time someone has contact with the bacteria until they become sick, but it could be as little as a few days.
The Hib vaccine is safe, and it prevents most children from getting serious Hib infections. It is one of the vaccines all children under 5 years of age should get. Ask your doctor if your child should get the Hib vaccine. Older children and adults with certain medical problems, such as not having a spleen or having a weakened immune system, should also get the Hib vaccine. Children who are under 24 months of age who have had Hib disease may be at risk for re-infection if the body’s immune response wanes, and should also be vaccinated. Your doctor can decide if you or your child needs Hib vaccine.
Page last updated/reviewed: April 2026
