Which type of vaccine is produced by chemically combining a polysaccharide with a protein molecule?

The type of vaccine produced by chemically combining a polysaccharide with a protein molecule is a conjugate polysaccharide vaccine. This method enhances the immune response, particularly in young children, who may not respond strongly to polysaccharide antigens alone. The protein component helps to stimulate a stronger and longer-lasting immune response, leading to better protection against the disease.

In conjugate vaccines, the polysaccharide component is often derived from the capsule of certain bacteria, which can be poorly immunogenic on its own. By linking it to a protein carrier, the body’s immune system can better recognize and respond to it, ultimately providing immunity not just to the polysaccharide part but as well to the entire pathogen.

This mechanism is essential for vaccines against diseases like Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae, where the polysaccharide capsules play a crucial role in virulence but require the boosting effect of the protein component to elicit a sufficient immune response in the population, particularly in vulnerable groups such as infants and young children.