What is the difference between vaccine conjugate and Polysaccharide vaccine?

Conjugate vaccines:

- Are made by chemically linking a polysaccharide antigen to a protein carrier, such as tetanus toxoid or diphtheria toxoid.

- This process makes the polysaccharide antigen more immunogenic, meaning that it is more likely to produce a strong immune response.

- Conjugate vaccines are used to protect against diseases caused by bacteria, such as Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae (pneumococcus).

Polysaccharide vaccines:

- Are made from purified polysaccharides, which are complex carbohydrates that make up the cell walls of bacteria.

- Polysaccharide vaccines are less immunogenic than conjugate vaccines, so they are typically used in children who are older than 2 years old.

- Polysaccharide vaccines are used to protect against diseases caused by bacteria, such as Neisseria meningitidis (meningococcus) and Salmonella Typhi (typhoid fever).

Comparison:

| Feature | Conjugate vaccine | Polysaccharide vaccine |

|---|---|---|

| Composition | Polysaccharide antigen linked to a protein carrier | Purified polysaccharides |

| Immunogenicity | More immunogenic | Less immunogenic |

| Age of recipients | Can be used in children of all ages | Typically used in children 2 years and older |

| Diseases prevented | Hib, pneumococcus | Meningococcus, typhoid fever |