Serotype distribution of Streptococcus pneumoniae among healthy carriers and clinical patients: a systematic review from Iran

Streptococcus pneumoniae is associated with high morbidity and mortality in the world. Commercially licensed and available pneumococcal conjugate vaccines (PCVs) contain 10 (PCV10) and 13 (PCV13) pneumococcal serotypes. The most common serotypes of S. pneumoniae causing clinical diseases and carriers of S. pneumoniae in Iran are not yet known. Reviewing and reporting trends in the distribution of pneumococcal serotypes in Iran will be useful for policy-making as PCV is being introduced into Iran’s routine immunization program. Here, we report a systematic literature review of studies regarding S. pneumoniae serotype distribution in clinical and carrier patients in Iran. MEDLINE (via PubMed), Scopus, Embase, Ovid, Google Scholar, Web of Science, and the Iranian Database were used to identify relevant papers published from 1 January 2000 to 21 August 2019. The search returned 8 relevant articles. Among serotypes causing invasive pneumococcal diseases (IPD), serotype 23F (16.4%) was the most circulating serotype followed by 19F (15.2%), 19A (11.3%), 6A/B (9.2%), 9 V (5.8%), and 11A (5.14%). In carrier patients, the most common serotypes were, in rank order, 6A/B (10%), 19F (9%), 14(6.2%), 17F (4.8%), and 20(4.5%). Vaccine coverage among IPD patients would be 67.1% for PCV10-TT and 73.8% for PCV13. The present review demonstrates that the serotypes which were most responsible for disease in Iran are included in PCV10-TT and PCV13. However, sentinel surveillance must be continued in representative parts of the country to assess changing trends in the distribution of pneumococcal serotypes and their implications for vaccine selection and rollout in Iran.