Pneumococcal 21-Valent Conjugate Vaccine

**Semantic type:** Immunologic Factor|Pharmacologic Substance

**Definition:** A pneumococcal conjugate vaccine containing 21 different strains of the bacterium Streptococcus pneumoniae, that is used for the prevention of pneumococcal disease. The pneumococcal 21-valent conjugate vaccine contains capsular antigen polysaccharides derived from the S. pneumoniae serotypes 3, 6A, 7F, 8, 9N, 10A, 11A, 12F, 15A, 15B (de-O-acetylated prior to conjugation), 16F, 17F, 19A, 20A, 22F, 23A, 23B, 24F, 31, 33F, and 35B that are individually conjugated to a nontoxic diphtheria cross-reactive material 197 (CRM197) carrier protein to create 21 individual conjugates. Upon intramuscular vaccination, pneumococcal 21-valent conjugate vaccine induces active immunization against these 21 different serotypes of S. pneumoniae and protects against pneumococcal disease. As the de-O-acetylated polysaccharide from serotype 15B has a molecular structure similar to the polysaccharide from serotype 15C, this polysaccharide also induces an immune response and kills S. pneumoniae serotype 15C.

**Synonyms:** - CAPVAXIVE - PCV 21 - PCV 21 Vaccine