How are polysaccharides coupled to proteins vaccines?

— Limitations of PS vaccines: Unable to activate TH cells — Humoral T-independent response, too low before the age of 2 years — IgM antibodies: no phagocyte opsonisation — Low affinity — Solution = Conjugated vaccine: PS and protein — The protein acts as a carrier — Induction of TH and T-dependent IgG humoral response — Vaccine against Haemophilus influenzae Group B — Haemophilus influenzae Group B is the leading cause of meningitis in children under 5 — Vaccine made of polysaccharides coupled to a carrier protein — Provides efficient protection of the newborn