Of the many possible candidate antigens for subunit vaccine development, carbohydrates are particularly appealing because of their ubiquitous presence on the surface of all living cells, viruses, and parasites as well as their known interactions with both innate and adaptive immune cells. Carbohydrates have also garnered attention in other aspects of vaccine development, for example, as adjuvants that enhance the immune response by either activating innate immune responses or targeting specific immune cells. Additionally, carbohydrates can function as immunomodulators that dampen undesired humoral immune responses to entire protein antigens or specific, conserved regions on antigenic proteins. 
Spectecular review by Cornell UniversityColumbia University and Stanford University (Sophia HulbertPrimit DesaiMichael JewettMatt DeLisa and Asher Williams)

Glycovaccinology: The design and engineering of carbohydrate-based vaccine components – ScienceDirect