Haemophilus Influenzae Type B (Hib) Vaccination

What is the haemophilus influenzae type b (Hib) vaccine?

The haemophilus influenzae type b (Hib) vaccine protects against infections caused by the Hib bacteria. Hib infections can result in serious, life-threatening conditions such as:

Epiglottitis (infection of the windpipe)
Meningitis (infection of the lining of the brain and spinal cord)
Pneumonia (infection of the lungs)
Sepsis (severe immune reaction)

Although Hib infections can be treated using antibiotics and other therapies, there can be long-lasting consequences. These include hearing loss, learning disabilities, loss of limbs, and seizures.

In Singapore, Hib cases are rare due to the haemophilus influenzae type b vaccine being offered under the National Childhood Immunisation Schedule (NCIS).

How the haemophilus influenzae type b (Hib) vaccine works

The Hib vaccine is a conjugate vaccine that contains substances from diphtheria, meningococcus, or tetanus bacteria. The vaccine triggers an immune response so that the body produces antibodies against potential infection by Hib bacteria.

Types of haemophilus influenzae type b (Hib) vaccines

Haemophilus influenzae type b conjugate vaccines include:

PRP-T. This vaccine uses tetanus toxoid as a carrier protein to conjugate with the haemophilus influenzae type b polysaccharide (PRP). It provides immunity against both Hib and tetanus.
PRP-OMP. This vaccine uses an outer membrane protein complex (OMPC) from Neisseria meningitidis as a carrier protein. It is used in combination with other vaccines like hepatitis B or diphtheria-tetanus-pertussis (DTaP).
HbOC. This vaccine employs a protein carrier derived from Neisseria meningitidis.

Haemophilus influenzae type b polysaccharide vaccines include:

Unconjugated PRP. This vaccine consists of purified Hib polysaccharide alone. However, it is less effective in infants and does not induce a robust immune response as compared to conjugate vaccines.

In Singapore, only conjugate haemophilus influenzae type b vaccines are administered as part of the National Childhood Immunisation Schedule (NCIS).

Differences between haemophilus influenzae type b (Hib) vaccines

Conjugate vs polysaccharide

Conjugate vaccines are conjugated with a protein carrier to enhance the immune response, especially in infants. This leads to better and longer-lasting immunity.
Polysaccharide vaccines rely solely on the Hib polysaccharide. While they may be suitable for older children and adults, they are less effective in infants.

Carrier proteins

Different vaccines use different carrier proteins. For example, PRP-T uses tetanus toxoid, PRP-OMP uses OMPC from Neisseria meningitidis, and HbOC uses a protein carrier derived from the same bacterium.

Combination vaccines

Some Hib vaccines are combined with other vaccines, such as hepatitis B or diphtheria-tetanus-pertussis (DTaP), to reduce the number of shots needed.

Number of doses

The number of doses required for each vaccine may vary. Some vaccines may require fewer doses for primary immunisation, while others may have different schedules.

Why do you need the haemophilus influenzae type b (Hib) vaccine?

The Hib vaccine is very effective in preventing Hib infection, which causes life-threatening illnesses like meningitis, sepsis, and pneumonia, which can cause lasting damage to the affected organs.

When do you need the haemophilus influenzae type b (Hib) vaccine?

The haemophilus influenzae type b vaccine is part of Singapore’s National Childhood Immunisation Schedule (NCIS). It is given in 3 doses at 2, 4, and 6 months of age, with 2 additional boosters given at 18 months and 10 – 11 years of age.

The Hib vaccine is also recommended for adults who have a compromised immune system, are currently undergoing chemotherapy, and for those who have had their spleen removed.

Who should not receive the haemophilus influenzae type b (Hib) vaccine?

The Hib vaccine should not be given to those who:

Have an allergy to any ingredient in the vaccine
Have had a severe reaction after receiving a previous dose of the vaccine
Are younger than 6 weeks

How do you prepare for the haemophilus influenzae type b (Hib) vaccine?

There is no specific preparation prior to receiving the Hib vaccine. However, you should inform your doctor if you are feeling unwell, taking any medication, or have a history of bleeding disorders.

What can you expect when getting the haemophilus influenzae type b (Hib) vaccine?

The Hib vaccine is administered via injection into the muscle, such as the thigh muscle in infants and young children, and the upper arm in older children and adults.