There are >100 known serotypes of S. pneumoniae, with some serotypes grouped into serogroups based on similarities in the polysaccharide capsule. Of the numerous pneumococcal serotypes, only a subset is responsible for the majority of cases of invasive pneumococcal disease (IPD). The distribution of serotypes that cause disease varies over time and by age, disease syndrome, disease severity, geographical region and presence of AMR genes.
A 2010 systematic review found that before the introduction of PCV7, 6 to 11 serotypes accounted for ≥70% of global and regional IPD cases, with 7 serotypes (1, 5, 6A, 6B, 14, 19F, 23F) being the most prevalent globally Go to footnote 1. More recently, the Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) project, which compiled data from 45 countries with stable surveillance systems, found that following sustained, high coverage with PCV13 or PCV10, 10 vaccine serotypes (1, 3, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F in all age groups, and serotype 4 in adults) remain among the top 30 serotypes causing IPD. Serotype replacement with other non-vaccine serotypes was also common. Go to footnote 2, Go to footnote 3
To note that with the introduction of PCV, the more recent availability of new formulations and WHO issuing recommendations about the higher valency vaccines, there is an impact on the circulating serotypes and it is no longer possible to determine the pre-vaccination serotype prevalence.
- Go back to footnote reference 1
Johnson HL, Deloria-Knoll M, Levine OS, Stoszek SK, Freimanis Hance L et al. (2010). Systematic evaluation of serotypes causing invasive pneumococcal disease among children under five: the pneumococcal global serotype project. PLoS Med. 7(10):e1000348. doi: 10.1371/journal.pmed.1000348.
- Go back to footnote reference 2
Garcia Quesada M, Yang Y, Bennett JC, Hayford K, Zeger SL et al. (2021). Serotype distribution of remaining pneumococcal meningitis in the mature PCV10/13 period: findings from the PSERENADE project. Microorganisms. 9(4):738. doi: 10.3390/microorganisms9040738.
- Go back to footnote reference 3
Garcia Quesada M, Peterson ME, Bennett JC, Hayford K, Zeger SL et al. (2025). Serotype distribution of remaining invasive pneumococcal disease after extensive use of ten-valent and 13-valent pneumococcal conjugate vaccines (the PSERENADE project): a global surveillance analysis. Lancet Infect Dis. 25(4):445–456. doi: 10.1016/S1473-3099(24)00588-7
