Polysackaridvacciner

Polysackaridvacciner, commonly referred to in English as polysaccharide vaccines, are vaccines that use purified polysaccharide components from the capsules of bacteria to provoke an immune response. They represent a class of subunit vaccines that target surface polysaccharides to induce antibody production against specific bacterial serotypes.

Their immunological profile is characterized by a T-independent response. This means they primarily stimulate B cells without strong help from T cells, often leading to limited immunological memory and shorter-lasting protection. This effect is especially pronounced in young children, who may have weaker or more transient responses to plain polysaccharide antigens. As a result, plain polysaccharide vaccines have lower effectiveness in certain age groups and may require booster doses to maintain protection.

To overcome these limitations, many polysaccharide vaccines are conjugated to protein carriers, transforming the immune response into a T-dependent one. Conjugation improves immunogenicity in young children and promotes immunological memory and booster responsiveness. This shift underpins the widespread use of conjugate vaccines for pathogens such as Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis in modern immunization programs.

Common examples of polysaccharide vaccines include pneumococcal polysaccharide vaccines (such as the 23-valent formulation) for adults and at-risk groups, and various meningococcal polysaccharide vaccines. While conjugate versions are often preferred in pediatric programs, plain polysaccharide vaccines remain in use for certain populations and serotypes, and continue to play a role in public health immunization strategies.