Search: Go
Immunization Science
Immunization Issues
Vaccines and the Diseases they Prevent
Health Professionals
About NNii

Vaccine Information

Haemophilus Influenzae type b (Hib)

Entry last updated: May 27, 2004

- Understanding the Disease
- Available Vaccines
- History of the Vaccine
- Who Should and Should Not Receive the Vaccine
- Dose Schedule
- Effectiveness of the Vaccine
- Known Side Effects
- Related Issues
- Key References and Sources of Additional Information
- State Vaccine Requirements
- Important Facts for Parents to Know
- Frequently Asked Questions
- CDC Vaccine Information Statement

Understanding the Disease

Haemophilus influenzae type b (Hib) is a bacterium that can infect the outer lining of the brain causing meningitis. Hib is transmitted from person to person through mucus droplets that are spread by coughing or sneezing. Invasive Hib disease occurs most often at three months to three years of age, peaking at six to seven months of age. The disease is uncommon after age five years.

Hib can cause a wide variety of serious infections, including pneumonia, severe throat swelling that makes breathing difficult (epiglottitis), and infections of blood, bones, joints, and the covering of the heart. 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.

Available Vaccines

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

Product: ActHIB® (Hib)
Manufacturer: Aventis Pasteur
Year Licensed: 1993

Product: HibTITER® (Hib)
Manufacturer: Wyeth Lederle
Year Licensed: 1990

Product: PedvaxHIB® (Hib)
Manufacturer: Merck
Year Licensed: 1989

Product: Comvax® (HBV-Hib)
Manufacturer: Merck
Year Licensed: 1996

For information on the thimerosal content in these vaccines, see the Food and Drug Administration at
or Johns Hopkins University's Institute for Vaccine Safety at

History of the Vaccine

The first Hib vaccine was licensed in 1985. Scientists later reformulated the vaccine so that it would be effective in children under 18 months of age, and the FDA licensed this improved version in 1987. The currently used Hib vaccine protects infants as young as six weeks old.

Prior to universal Hib immunization, Hib was the most common cause of bacterial meningitis in infants and preschool-age children, and caused approximately 20,000 cases of invasive disease annually.

Who Should and Should Not Receive this Vaccine

Who should receive the vaccine?

  • Due to the high risk of disease in children, all children younger than five years should receive the Hib vaccine, beginning at two months of age.
  • Children over five years usually do not need Hib vaccine. Older children or adults with specific health conditions such as sickle cell disease, HIV/AIDS, removal of spleen, bone marrow transplant, or cancer treatment with immune-suppressant drugs need to be protected from Hib by the vaccine.

Unimmunized children are at increased risk of developing Hib when they are:

  • Daycare attendees
  • Household contacts of someone with Hib
  • Those with a low socioeconomic status
  • African-American
  • Native American
  • Immunocompromised because of sickle-cell disease, leukemia, human immunodeficiency virus (HIV) infection, or the absence of the spleen

Who should not receive the vaccine?

  • Children younger than six weeks old
  • People who have had a life-threatening allergic reaction (anaphylaxis) to a previous dose of Hib vaccine should not receive additional doses.
  • People who are moderately or severely ill should consult with their physician before receiving any vaccine.

This vaccine is recommended by:

  • Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention
  • American Academy of Pediatrics
  • American Academy of Family Physicians

The complete childhood immunization schedule can be found at:

Dose Schedule

Children should get the Hib vaccine at 2, 4, 6*, and a booster at 12 to 15 months of age.

*Depending on which Hib vaccine is used, a child may not need the dose at six months of age. The doctor or nurse will know whether or not this dose is needed.

Effectiveness of the Vaccine

Hib is one of only two vaccines that are more effective at providing immunity than natural infection is--the other is tetanus vaccine. Although the Hib vaccine prevents only one form of meningitis, it has nearly eliminated what was once the most common cause of bacterial meningitis in infants and children in the United States. Since Hib vaccines were introduced, the incidence of invasive Hib disease in infants and children in the U.S. has decreased by 99%.

Healthy recipients of Hib vaccine may be susceptible to Hib disease for one to two weeks until antibodies are developed.

Children at increased risk for Hib because of severe combined immunodeficiency syndrome or IgG2 deficiency, and some children with severe immune deficiency from HIV infection or who are receiving chemotherapy for malignant neoplasms (growths), may not develop protective antibodies from the vaccine and may, or may not, benefit from additional doses.

Known Side Effects

Approximately 25% of children who receive the Hib vaccine experience mild side effects such as pain, redness, or swelling at the site of the shot, while more serious reactions are infrequent.

Studies have shown that children who receive the Hib vaccine in combination with or at the same time as the DTaP vaccine are no more likely to experience side effects than children who receive only the DTaP vaccine.

Related Issues

Questions about the relationship between diabetes and the Hib vaccine have surfaced. Scientific evidence has not supported a relationship. The rate of diabetes in vaccinated children has been compared with the rate in unvaccinated children who were born before the vaccine was available.

No association between the vaccine and the development of diabetes was found.

Please see the following for further information:

Key References and Sources of Additional Information

Also see our image gallery of diseases.

Including available vaccines, history of the vaccine, who should and should not receive it, dose schedules, effectiveness, known side effects, and related issues.

Haemophilus Influenzae type b (Hib) Vaccine State Requirements

Check to see if your state requires this vaccine.

Important Facts for Parents to Know about the Haemophilus Influenzae type b (Hib) Vaccine

A fact sheet that gives basic information on this disease, as well as the effectiveness and possible side effects of the vaccine that can prevent it.

Frequently Asked Questions about the Haemophilus Influenzae type b (Hib) Vaccine

A fact sheet with in-depth answers to common questions about this vaccine.

CDC Vaccine Information Statement for Haemophilus Influenzae type b (Hib)

Information provided by the Centers for Disease Control and Prevention on specific vaccines and the diseases they can prevent. Healthcare providers are required to give these to their patients before administering a vaccine.

Home | About NNii | Contact Us | Contribute | Disclaimer | Site Map