21-valent pneumococcal conjugate vaccine (PCV21) (PCV21)

The 21-valent pneumococcal conjugate vaccine (PCV21), commercially known as Capvaxive (V116), is an advanced immunizing agent designed to prevent invasive pneumococcal disease and pneumonia caused by Streptococcus pneumoniae in adults (2, 5). It consists of purified capsular polysaccharides from 21 distinct serotypes (3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15B, 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F, and 35B), each individually conjugated to the CRM197 carrier protein (2, 3). This conjugation is critical as it transforms the polysaccharides from T-cell independent antigens into T-cell dependent ones, enabling the recruitment of T-helper cells and the subsequent production of high-affinity IgG antibodies and long-term immunological memory (10, 17). PCV21 is specifically tailored for the adult population, targeting serotypes responsible for approximately 85% of invasive pneumococcal disease in adults aged 65 and older, including eight unique serotypes not covered by previously licensed conjugate vaccines (8, 11). The vaccine's primary mechanism of action is the induction of serotype-specific opsonophagocytic activity (OPA), which enhances the immune system's ability to recognize, ingest, and destroy the bacteria (1, 3). By providing broader coverage than earlier 13-, 15-, or 20-valent formulations, PCV21 addresses the shifting epidemiology of pneumococcal disease and offers a more comprehensive preventative option for at-risk adult populations (10, 13).

Other names

V116CapvaxivePneumococcal 21-valent conjugate vaccine21-valent pneumococcal capsular polysaccharide-CRM197 conjugate

Induction of serotype-specific opsonophagocytic antibodies through a T-cell dependent immune response. The CRM197 carrier protein converts T-cell independent polysaccharides into T-cell dependent antigens, facilitating the recruitment of T-helper cells and the production of high-affinity IgG antibodies and memory B-cells.