Polüsahhariidvaktsiinid

Polüsahhariidvaktsiinid are a type of vaccine that uses polysaccharide antigens, which are long chains of sugar molecules, to stimulate an immune response. These polysaccharides are typically derived from the outer capsule of bacteria. Because the immune system's response to pure polysaccharides can be weak, especially in young children and infants, these vaccines are often conjugated. Conjugation involves chemically linking the polysaccharide to a carrier protein. This conjugation significantly enhances the immunogenicity, leading to a stronger and more durable immune response, including the development of immunological memory.

The development of conjugated polysaccharide vaccines has been a major advancement in preventing bacterial infections. Before conjugation, vaccines targeting encapsulated bacteria like *Haemophilus influenzae* type b (Hib), *Streptococcus pneumoniae*, and *Neisseria meningitidis* had limited effectiveness in the most vulnerable populations. By attaching the bacterial polysaccharide to a protein, T-cells are activated, which in turn help B-cells produce antibodies against the polysaccharide. This process is crucial for providing protective immunity against diseases such as meningitis, pneumonia, and sepsis caused by these bacteria.

Polysaccharide vaccines are administered through injection. Their efficacy is measured by the development of antibodies against the specific bacterial capsule. Side effects are generally mild and similar to other vaccines, potentially including pain or redness at the injection site, and low-grade fever. Extensive clinical trials and post-marketing surveillance confirm their safety and effectiveness in reducing the incidence of serious bacterial infections. These vaccines are a cornerstone of routine immunization programs worldwide.