What are the different serotypes of S. pneumoniae targeted by different pneumococcal vaccines?

S. pneumoniae bacteria are serotyped based on the polysaccharides in the outer capsule of the bacteria. Serotypes vary in how common they are and in what percentage of pneumococcal disease they cause.

Among the PCV vaccines, PCV13 includes serotypes: 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F and 23F. PCV15 includes all PCV13 serotypes plus 22F and 33F. PCV20 includes all PCV15 serotypes plus 8, 10A, 11A, 12F, and 15B. PPSV23 vaccine does not contain serotype 6A, but contains 19 other serotypes present in PCV20, plus serotypes 2, 9N, 17F, and 20.

PCV21 is designed to target additional serotypes causing a significant proportion of disease in adults that are not prevented by the vaccines approved for children. It does not contain 10 serotypes found in other pneumococcal vaccines approved for children (1, 4, 5, 6B, 9V, 14, 18C, 19F, 23F, 15B, or 2). Instead, it contains an additional 11 serotypes not found in PCV20: 9N, 17F, 20, 15A, 15C, 16F, 23A, 23B, 24F, 31, and 35B. Because of these differences, CDC estimates that PCV20 targets serotypes that cause between 54% and 65% of invasive pneumococcal disease (IPD) in adults, and PCV21 targets serotypes that cause between 77% and 85% of IPD in adults.