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Haemophilus Influenza Type B (HIB) Disease & Vaccine Information

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What is Haemophilus Influena Type B (Hib)

HIB: The Disease

Haemophilus influenza (H. influenzae) is a bacterial infection that was erroneously first identified in 1892 as the cause of influenza. It was later determined to be an invasive bacterial infection that is exclusively a human pathogen spread by airborne droplets through sneezing or coughing, or by direct contact with secretions or fomites. Six major serotypes of H. influenzae have been identified and labeled with the letters a through f. Some strains, which don’t have a polysaccharide capsule, are still untyped.

The most common symptoms of severe Hib infection are fever and altered central nervous system function. Less common symptoms can be osteomyelitis, septic arthritis, pericarditis, orbital cellulitis, endophthalmitis, urinary tract infection, abscesses, and bacteremia. Learn more about HIB

HIB Vaccine

The Haemophilus influenzae type b (Hib) polysaccharide-protein conjugate vaccine has been available in the U.S. since December 1987. Conjugation is the process of chemically bonding a polysaccharide to a protein “carrier” to increase the effectiveness of the polysaccharide antigen. Two conjugate Hib vaccines are licensed for use in the U.S. for infants as young as 6 weeks old. A third is approved only for the last dose of Hib among children ages 12 months and older. Three combination vaccines that contain Hib conjugate vaccine are also available, for a total of six vaccines containing Haemophilis B that are licensed for vaccination and distribution in the U.S.

One of the three combination vaccines was only approved by the FDA on June 14, 2012, a Meningococcal Groups C and Y and Haemophilus b tetanus toxoid conjugate vaccine for infants and children ages 6 weeks through 18 months. None of the Hib vaccines protect against any other types of Haemophilus infection than type b. It also does not protect against meningitis caused by any other bacteria. It is not known whether Hib vaccine protects against ear infections. Learn more about HIB vaccine

HIB Quick Facts


  • Hib is spread through person-to-person transmission, mostly through the air. It’s often found in the respiratory tracts of adults with no symptoms or adverse effects. Hib has to get into the bloodstream for it to cause meningitis or severe infections of the bones and joints.
  • Hib is mostly a disease of young children under the age of 5 years old. Before the vaccine was introduced in the U.S., children who became sick from Hib were usually under 2 years old, and mostly between 6 and 7 months old.
  • In general, Hib disease is not considered very contagious. Before the vaccine most children acquired natural immunity to Hib by the time they were 5 or 6 years old. Continue reading quick facts

HIB Vaccine

  • There are five different Haemophilus influenzae type b (Hib) vaccines available in the U.S., including three for infants as young as 6 weeks old; The five vaccines are: ActHIB; Hiberix; PedvaxHIB; Pentacel and Menhibrix. A sixth vaccine, Comvax (combined with Hepatitis B recombinant) is an approved vaccine but production was discontinued by Merck in December 2014.
  • As of 2014, the CDC recommends infants receive Hib vaccine between 2 to 6 months of age with an additional booster dose between 12 and 15 months of age. Continue reading quick facts...

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