Conjugate subunit vaccines
Conjugate subunit vaccines also create a response against the molecules in the pathogen’s capsule. In comparison to plain polysaccharide vaccines, they benefit from a technology that binds the polysaccharide to a carrier protein that can induce a long-term protective response even in infants.
Various protein carriers are used for conjugation, including diptheria and tetanus toxoid. Conjugate subunit vaccines, can therefore prevent common bacterial infections for which plain polysaccharide vaccines are either ineffective in those most at risk (infants) or provide only short-term protection (everyone else).
The advent of conjugate subunit vaccines heralded a new age for immunization against disease caused by encapsulated organisms such as meningococcus, Haemophilus influenzae type b (Hib) and pneumococcus.
WHO recommends that children receive Haemophilus influenzae type b (Hib)and pneumococcal conjugate vaccines. In addition, the meningococcal A vaccine introduced in Africa is also a conjugated subunit vaccine.