What type of vaccine links a highly immunogenic protein with a poorly immunogenic capsule polysaccharide?

Conjugated vaccines are designed to enhance the immune response to polysaccharide antigens by linking them to a highly immunogenic protein. This approach is particularly effective for polysaccharides that might otherwise have a weak immunogenicity, especially in infants and young children. By combining the weakly immunogenic polysaccharide capsule of certain bacteria with a protein that elicits a strong immune response, the vaccine helps to generate a more robust and long-lasting immunity against the encapsulated bacterium.

An example of this is the Haemophilus influenzae type b (Hib) vaccine, which conjugates the polysaccharide from the bacterial capsule with a carrier protein. This combination allows the immune system to recognize the polysaccharide effectively, promoting a better antibody response.

In contrast, inactivated and live attenuated vaccines do not utilize this specific strategy of linking polysaccharide and protein antigens. Inactivated vaccines contain killed pathogens, while live attenuated vaccines contain weakened forms of the pathogen itself. Subunit vaccines focus on using only specific pieces of the pathogen (often proteins), rather than combining polysaccharides and proteins for enhanced immunogenicity like conjugated vaccines do.