What is hib?

Short Answer

Hib disease is a group of serious illnesses caused by the bacteria Haemophilus influenzae type B that are spread through coughing and sneezing. It’s not as well known as other childhood diseases, but it is just as dangerous and can affect several organs in the body. The most common diseases caused by Hib are pneumonia, bacteria in the blood (occult febrile bacteremia), meningitis, inflammation of the tissue covering the windpipe (epiglottitis), inflammation of joints due to bacterial infection (septic arthritis), bacterial skin infection (cellulitis), middle-ear infection (otitis media), and inflammation of the sac around the heart (purulent pericarditis). Hib symptoms vary depending on the type of disease it causes. Almost all children (at least 95%) who get the recommended three to four doses of the vaccine will be protected from Hib disease.




Symptoms & Incubation

Hib disease causes different symptoms depending on which part of the body it affects. The most common type of Hib disease is meningitis. This is an infection of the covering of the brain and spinal cord. It causes the following:

  • Fever
  • Loss of alertness
  • Stiff neck


Hib disease can also cause:

  • Throat swelling that makes it hard to breathe
  • Joint infection
  • Skin infection
  • Pneumonia (lung infection)
  • Bone infection

The amount of time between infection and when symptoms appear is unknown.



Complications of Hib meningitis include blindness, deafness, mental retardation, learning disabilities, and death. About 5% of children (500 out of every 10,000) with Hib meningitis die despite antibiotic treatment.


Hib spreads when an infected person coughs or sneezes. Usually, the Hib bacteria stay in a person’s nose and throat and do not cause illness. If the bacteria spread into the lungs or blood, however, the person will likely get very ill. Hib is most commonly spread among family members and in child-care centers.

High-risk Populations
Babies and children younger than 5 years old are most at risk for Hib disease.


The Hib vaccine is available as:

  • Hib (alone)
  • Hib in combination with DTaP (Diphtheria-Tetanus-acellular Pertussis) vaccine
  • Hib in combination with recombinant hepatitis B (HBV) vaccine


Children should get three or four doses of the Hib vaccine at the following ages for best protection:

  • One dose at 2 months;
  • A second dose at 4months;
  • For some brands, one dose at 6 months; and
  • A final dose at 12 through 15 months of age.

It is safe to get the Hib vaccine at the same time as other vaccines, even for babies.

Safety & Side Effects

The Hib vaccine is very safe, and it is effective at preventing Hib disease. Vaccines, like any medicine, can have side effects. But severe side effects from the Hib vaccine are very rare, and mild effects usually include redness, warmth, or swelling at the injection site and/or a fever.

Since the Vaccine Was Introduced…
Before the Hib vaccine, Hib disease was the most common cause of meningitis in children younger than 5 years in the U.S. About 20,000 children got severe Hib disease each year, and about 1,000 died. Today, with the vaccine, cases of severe Hib disease have dropped by more than 99%.