Haemophilus influenzae type b (Hib) bacteria are surrounded by polysaccharide capsules, which make the bacteria resistant to attack by white blood cells. However, human blood serum contains antibodies, which render the bacteria vulnerable to attack. The vaccine, which is composed of the purified polysaccharide from Hib bacterial cells, stimulates production of anticapsular antibodies and provides active immunity to the Haemophilus influenzae type b bacteria represented by the polysaccharide in the vaccine.

Haemophilus b polysaccharide vaccine, unlike the conjugate vaccine, predominantly stimulates B-cells to produce antibodies. This is known as being T-cell independent and is characteristic of polysaccharide vaccines. The initial stimulation of T-cells followed by stimulation of B cells (known as a T-cell response) is particularly important in young children to ensure adequate and persisting antibody production. Stimulation of T-cells also results in an anamnestic response to future doses of the vaccine and future natural exposure to Haemophilus influenzae type b. The poor T-cell response stimulated by the polysaccharide vaccine is thought to be one reason why the polysaccharide vaccine is not adequately immunogenic in children up to 18 months of age and may not be fully immunogenic in children 18 to 24 months of age. In addition, lack of initial T-cell stimulation probably is the reason that repeat doses of the polysaccharide vaccine do not boost the antibody response consistently.

Active immunisation against invasive disease caused by Haemophilus influenzae type b in children from 2 months of age. This vaccine does not stimulate protection against diseases caused by different Haemophilus Influenzae serotypes and from other meningitis types caused by different pathogen agents.

Primary series-

• Under 13 months of age: Three 0.5 ml doses, with an interval of at least four weeks between doses, the first dose to be given not earlier than two months of age.
• 13 months of age and over: A single 0.5 ml dose. This vaccine is not recommended for healthy children aged more than four years.

Booster-

• Following completion of a primary series in which all three doses were administered before the age of 6 months, an additional (fourth) dose of Hib conjugate vaccine should be administered. The timing of the Hib conjugate booster dose should be in accordance with official recommendations.
• Children who were primed with this vaccine may be boosted with this vaccine or with another Hib conjugate vaccine. Similarly, This vaccine may be used to boost children who were primed with other Hib conjugate vaccines.

Administration

• The vaccine should be shaken before use.
• This should be administered intramuscularly in the anterolateral area of the thigh in infants. Do not administer intravascularly.
• One dose is 0.5 ml. For single and ten dose/vial presentations a sterile syringe and sterile needle should be used for each injection.
• Patients with thrombocytopenia or bleeding disorders may be vaccinated by the subcutaneous route.

Do not vaccinate in case of any known hypersensitivity to the vaccine components or a severe reaction to a previous dose. This vaccine will not harm individuals previously infected with the Hib bacteria. As with other vaccines, vaccination should be postponed in subjects suffering from acute severe febrile illness. The presence of a minor non-febrile infection, however, is not a contra-indication to vaccination.

Very common adverse reactions are tenderness, erythema, induration, unusual crying, irritability, vomiting, diarrhoea, change in eating habits, sleepiness, fever.

In the presence of congenital or acquired immune deficiency, this vaccine may be administered but a protective immune response may not be elicited. Although a limited immune response to the diphtheria toxin component may occur, vaccination with this vaccine does not substitute for routine diphtheria vaccination. This vaccine does not elicit protection against diseases caused by other H.influenzae serotypes and does not protect against meningitis caused by other pathogenic agents. This vaccine should under no circumstances be administered intravascularly.

Pregnancy & Lactation

No reproductive studies have been conducted in animals since vaccination against Hib in adults is uncommon. There is no accurate information on the safety of this vaccine in pregnancy therefore this vaccine should not be used in pregnancy or during lactation.