Hib (H. influenzae Type B) Vaccine

Medically Reviewed by Neha Pathak, MD on December 15, 2022
6 min read

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.

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 intellectual disability.

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.

Haemophilus influenzae is a form of bacteria that leads to some infections and diseases. It has six main types: a, b, c, d, e, and f. 

These bacteria are in your throat and nose. But they don't tend to cause issues unless they move to other parts of your body. Once they do, they can lead to infections.

Hib is type b. This form causes 95% of all serious infections.

Type b spreads from person-to-person through coughs and sneezes. The droplets from these have the bacteria. If you breathe them in, you can get sick.

You can also get Hib if you're around someone else for a long time who has it in their throat or nose. This can happen even if the person doesn't have any symptoms.

The good news is experts don't believe that Hib can live on non-living surfaces.

Young kids under 5 are most at risk. Adults over 65 are also at risk for Hib, as well as those with compromised immune systems. There are also other groups who have a higher chance of Hib. These include:

  • American Indian people
  • Alaska Native people

As well as those with:

  • Asplenia (people without a spleen)
  • HIV infection
  • Sickle cell disease
  • Antibody and complement deficiency syndromes (these are rare conditions that impact your ability to fight infections)
  • Cancer that requires chemotherapy, radiation therapy, or bone marrow stem cell transplant

Symptoms of Hib depend on the disease that it caused. You may have:

An ear infection. With this, your child may have a loss of appetite, pain, irritability, bad sleep, a fever, drainage, or a hard time hearing.

Cellulitis. This bacterial infection on your skin can cause tenderness, pain, swelling, warmth, blisters, discoloration, a fever and chills, or fatigue.

Bronchitis. This can cause a mucus-filled cough, wheezing, a fever, lack of energy, and shortness of breath.

Pneumonia. With this condition, you may have a fever and chills, a cough, shortness of breath, sweating, a hard time breathing, chest pain, a headache, muscle pain, or fatigue.

Meningitis. Symptoms of meningitis include a fever, headache, fatigue, a stiff neck, loss of appetite, nausea or vomiting, confusion, irritability, or seizures.

Epiglottitis. This makes it hard for you to swallow. You may have a sore throat, fever, raspy breathing, drooling, or a hard time breathing.

Septicemia (a bloodstream infection). With septicemia, you might develop pain in your abdomen, a fever and chills, nausea and vomiting, diarrhea, confusion or anxiety, fatigue, shortness of breath, or a hard time breathing.

Septic arthritis. You'll notice symptoms like joint pain and warmth, a fever, tenderness, swelling, and less range of motion.


Your doctor will use at least one lab test to diagnose you with Hib. They may take a sample of your:

  • Blood
  • Joint fluid
  • Spinal fluid
  • Pleural fluid (fluid in your chest)
  • Middle ear aspirate

First, they'll use a test called Gram staining. This will find bacteria in your samples. It'll show doctors what type of bacteria causes your condition. To confirm if you have Hib, your doctor might do a blood or body fluid culture.

Doctors aren't totally sure how long the incubation period is for Hib. But they believe it might only take a few days for signs to develop once you've been infected.

Your medical team will usually treat you with antibiotics to fight the infection. But sometimes, you need more than antibiotics to heal from Hib. If your illness is serious, you might have to go to the hospital. Here, you'll get other treatments for Hib. This might include:

  • IV (intravenous) steroids
  • Breathing support with an oxygen face mask or through intubation
  • Drugs to treat low blood pressure
  • Care for wounds in you have them
  • Drainage surgery if you have septic arthritis

No. Hib bacteria have 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.

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.

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 may need the vaccine if:

  • You've had your spleen removed or have sickle cell disease, leukemia, or HIV
  • Your immune system has been suppressed due to a condition or by a treatment, such as for cancer


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.

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.

If your child misses a dose, they should be given a catch-up shot at the next doctor visit. There is no need to start the series over again.

The child will be protected against getting Hib meningitis if they receive 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.