Polysaccharide vaccines are a type of subunit vaccine, which are made from components of a pathogen, incapable of causing disease but specifically selected to help stimulate an immune response.¹ Other examples of subunit vaccines also include conjugate vaccines and protein-based vaccines.

Polysaccharide vaccines contain chains of identical polysaccharides, which are sugar molecules derived from the surface of the target pathogen.² This part of the pathogen is recognised as ‘foreign’ by the immune system, and is large enough so that an immune response is initiated.^2,3 

The use of Polysaccharide Vaccines


Polysaccharide vaccines work well to protect against various types of infection, but this type of subunit vaccine may not work for all pathogens, as every pathogen is unique by nature.²

These vaccines offer a greater level of protection in older children and adults than in young children and infants, as the immature immune systems of younger children struggle to recognise and respond to these foreign polysaccharide antigens in order to mount an immune response.^2,4


Pfizer does not offer subunit Polysaccharide Vaccines.

Therefore, to offer greater protection in younger children against infections that are more common in infancy, polysaccharide antigens may be conjugated to a carrier protein to form a conjugate vaccine, which enables the antigens to be delivered to cells that they would not be able to access without the protein.²

 

1. Public Health England. The Green Book [published 2013; updated 2020]. Chapter 25: Pneumococcal. Available at https://www.gov.uk/government/publications/pneumococcal-the-green-book-chapter-25 Last accessed: May 2022
2. UPDATE REFERENCES