Despite its name, the bacterium called Haemophilus influenzae type b, or Hib, does not cause the flu. It does, however, cause Hib disease, a serious health threat to children, especially those under age 5. Fortunately, the Hib vaccine, available since 1992, provides safe and effective protection against that threat.
What Is Hib Disease?
Hib disease is an invasive bacterial infection that at one time was the most common cause of bacterial meningitis in young children; invasive means that germs spread to parts of the body that are normally germ-free. Meningitis is an infection of the membrane that covers the brain and spinal cord. Bacterial meningitis is a serious infection that can cause fever, decline in cognitive ability, coma, and death. It kills from 3% to 6% of the children who have it. And even when children survive, many of them are left with serious nerve and brain damage that can range from blindness to paralysis to mental retardation.
In addition to meningitis, Hib can cause pneumonia; epiglottitis, which is an infection in the throat that can cause breathing difficulties; blood infection; bone infection; and joint infection leading to arthritis.
The Hib germ is spread in droplets that come from sneezing or coughing. Before use of the vaccine, there were about 20,000 cases of Hib disease each year in children under age 5 -- 12,000 of which were meningitis -- and about 1,000 deaths per year.
Can the Hib Vaccine Cause Hib Disease?
No. The Hib bacterium has a coating; the Hib vaccine is made from this coating, which, when bonded with a protein, can cause the body’s defenses to build up immunity to Hib. Since the whole bacterium isn’t used, it cannot cause Hib infection and so cannot cause Hib disease.
Is the Hib Vaccine Safe and Can It Be Given With Other Vaccines?
The vaccine is safe. The most common side effects include soreness, swelling, or redness at the site of the injection. There are no serious side effects, and severe allergic reactions are rare.
It is safe to give the vaccine with other vaccines or in a combination vaccine. The Hib vaccine is generally given as part of a child’s regular vaccination routine.
Who Should Get the Vaccine?
The CDC recommends that the vaccine be given to children under age 5. Ideally, the first dose should be given at age 2 months.
Because Hib disease is very rare in older children and because most adults have antibodies for Hib in their system, the vaccine is not recommended for anyone ages 5 or older, unless they are at increased risk for Hib infection. Older children and adults at increased risk include:
- Anyone who has had his spleen removed and anyone who has sickle cell disease, leukemia, or HIV
- Anyone whose immune system has been suppressed due to a condition or by a treatment, such as for cancer
How Many Doses of the Hib Vaccine Are Needed?
Different vaccines have been licensed for use in the U.S. The vaccines are equally effective and one can be substituted for the other if the original vaccine the child received is not available. The number of doses that are required for full immunity -- either three or four -- depends on which vaccine is being used. For adults and older children who are at increased risk and have never been vaccinated, at least one dose of the vaccine is needed for protection.
When Should My Child Be Vaccinated?
The CDC recommends that an infant receive the first dose at age 2 months, the second dose at age 4 months, and the third dose, depending on which vaccine is being used, at age 6 months. Both vaccines require a booster shot sometime between ages 12 and 15 months.
No child younger than 6 weeks should receive the vaccine. Giving a child the vaccine during the first six weeks of life could cause a reaction that would prevent the body from responding to the later doses of the Hib vaccine. Most newborns have a natural immunity to Hib that was passed to them by their mother. This wears off eventually.
What Happens if My Child Misses a Dose of Hib Vaccine?
If your child misses a dose, he or she should be given a catch-up shot at the next doctor visit. There is no need to start the series over again.
Once a Child Has Received the Hib Vaccine, Can He or She Still Get Meningitis?
The child will be protected against getting Hib meningitis if he or she receives the Hib vaccine. But there are other germs that can cause meningitis, so it’s still possible to develop meningitis at some point. The risk, though, is far less than it would be without the Hib vaccine.