Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

4.1     Pharmacodynamic Properties

VACCINE AGAINST HAEMOPHILUS INFLUENZAE TYPE B INFECTIONS
(J: anti-infectious)
The Haemophilus influenzae type b vaccine provides immunity against Haemophilus influenzae type b invasive infections.
In humans, the capsular polysaccharide (polyribosil ribitol phosphate: PRP) induces an anti-PRP serological response. However, as for any polysaccharide antigen, the nature of the immune response is thymo-independent, characterised by the absence of a booster effect when repeated injections are performed and by a low immunogenicity in infants and toddlers. The covalent bond of the Haemophilus influenzae type b capsular polysaccharide to the tetanus protein enables the conjugate vaccine to behave like a thymo-dependent antigen, resulting in a specific anti-PRP serological response in infants and toddlers with the induction of specific IgG and the establishment of an immune memory.
The study of the functional activity of the PRP-specific antibodies induced by the Haemophilus influenzae type b conjugate vaccine in infants and toddlers, and children demonstrated their bactericidal and opsonising activities.
Immunogenicity studies in infants and toddlers vaccinated from 2 months of age demonstrated that practically all of them had an anti-PRP antibody titre ≥ 0.15 µg/ml after administration of the third dose (and ≥ 1 µg/ml for approximately 90 % of them). In infants younger than 6 months of age who received three doses of Haemophilus influenzae type b conjugate vaccine, a booster injection administered 8 to 12 months later induced a very significant increase in the mean titre of the PRP antibodies.

Pharmacokinetic Properties