Serotypes of Streptococcus pneumoniae in children younger than 5 years after conjugate pneumococcal vaccines.

Abstract

Introduction. Immunization with pneumococcal conjugate vaccines has reduced invasive pneumococcal disease caused by vaccine serotypes. However, serotype replacement has been observed, when cases caused by non-vaccine serotypes are reported. Objective. To describe the distribution of serotypes isolated from invasive pneumococcal disease cases in children under 5 years of age in El Salvador, after the introduction of pneumococcal conjugate vaccines. Methodology. Descriptive study of the National Reference Laboratory Streptococcus pneumoniae data base, isolated from children under 5 years of age with invasive pneumococcal disease, from 2011 to 2017. The 61 isolated serotypes were classified into vaccine 29 and non-vaccine 32 serotypes, depending on whether or not they were contained in 7 or 13 valent conjugated pneumococcal vaccines. The data was exported to a Microsoft Excel 2013 spreadsheet, where it was analyzed using descriptive statistics. Results. From 2011 to 2017, 61 cases of invasive pneumococcal disease were reported in children under 5 years of age, 29 of them caused by vaccine serotypes and 32 by non-vaccine serotypes. The vaccine serotypes showed a downward trend, registering zero cases during 2016 and 2017. Non-vaccine serotypes showed an upward trend. The vaccine serotypes isolated most frequently were 9V, 14 and 19A, while the non-vaccine serotypes were: 8, 10A, 15A and 18A. Conclusions. There was a decrease in the number of cases of invasive pneumococcal disease due to vaccine serotypes from 2011 to 2017; in parallel, serotype replacement was identified.

Alerta Year 2018, Vol. 1 No. 1: 11-17