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Haemophilus influenzae (Hib)

Even though it sounds like Haemophilus influenzae is in the flu family, it is a bacterium. Hib causes different types of infections ranging from mild ear infections to life-threatening blood, brain, lung, and spinal cord infections. The term “Haemophilus influenzae disease” is the name for any of the illnesses that the bacteria causes.

There are 6 different kinds of H. influenzae, Hib A through Hib F.  Hib B (commonly just called Hib) is the type that is most common and can be prevented through vaccination. Hib is spread through coughing or sneezing.  Not everyone who has the bacteria will get sick, but they can still spread the bacteria.

Symptoms of Hib depend on what part of the body it infects:

Lung Infection (Pneumonia) Bloodstream Infection Brain Infection (Meningitis)
  • Fever and chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Sweating
  • Chest pain
  • Headache
  • Muscle pain or aches
  • Excessive tiredness
  • Fever and chills
  • Excessive tiredness
  • Pain in the belly
  • Nausea with or without vomiting
  • Diarrhea
  • Anxiety
  • Shortness of breath or difficulty breathing
  • Altered mental status (confusion)
  • Fever
  • Headache
  • Stiff neck
  • Nausea with or without vomiting
  • Photophobia (eyes being more sensitive to light)
  • Altered mental status (confusion)
  • Babies with meningitis may be irritable, vomit or have no appetite, and seem slow or inactive.

Babies and children younger than 5 are at increased risk of Hib. More than half of Hib infections (50 – 65%) involve the membranes covering the brain (meningitis). Of people getting meningitis, 2 – 5% will die, and 15 – 30% of survivors will have permanent neurologic damage, including blindness, deafness, and intellectual disability.

Most children (95%) are protected from Hib disease after two or three doses. Before the vaccine, Hib was the leading cause of bacterial meningitis in children under five.  Each year 20,000 children got Hib disease, and 1,000 of them died. With vaccination, there are now only a few dozen cases a year.

The Hib vaccine is safe, and serious side effects are rare. The most common reactions are:

  • redness or swelling where the vaccine is received (usually seen in 5 – 30% of children)
  • a fever over 101°F (up to 5% of children)

A child needs three to four doses of Hib vaccine depending on which vaccine they receive.

Children should get Hib vaccine at:

  • 2 months
  • 4 months
  • 6 months (depending on the vaccine)
  • 12 – 15 months

Talk to your healthcare provider about what vaccines your family needs.

Does your baby need a Hib vaccine? Download our Hib vaccine fact sheet to prepare for your appointment.

Learn more

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How do I know this information is credible?

We work for parents so we make sure that parent concerns are addressed using facts and science and our content is reviewed by experts who have spent their careers studying vaccines. Learn more about how we ensure we are bringing you the best information to help you make healthy choices for your family.

Before the Hib vaccine, one in 200 children under 5 developed Hib disease. A little more than 3.8 million babies are born in the U.S. every year. Without the Hib vaccine, 19,000 children would be at risk of Hib 380 – 950 children would die 5,700 children would suffer permanent neurological damage But if all U.S. children born in a year got the Hib vaccine, between 950 – 5,700 would have a sore arm for a day or so. Which outcome would you choose? Don’t let anyone tell you different – the vaccine is ALWAYS safer than the disease.
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