Backgrounds:

S. pneumoniae remains a leading cause of meningitis and/or septicemia worldwide, especially among children <2 years old, who are at higher risk of pneumococcal disease. The introduction of pneumococcal conjugate vaccines (PCV) has changed the epidemiology of the disease.

Methods

During 2010-2021, 155 cases of S. pneumoniae meningitis and/or septicemia were studied in children up to 16 years.S. pneumoniae and serotype was identified by molecular methods (mPCR and CST).

Results:

The overall incidence was 1.31/100,000, ranging from 1.62 in children 0-4 years old to 0.06 in adolescents. Among the notified cases, septicemia was the main clinical presentation (40.6%), followed by meningitis (38.7%) and septicemia and meningitis (20.6%). Case fatality ratio was 3.87%.

During the study period, a decrease in PCV-13 serotypes was observed with a simultaneous increase of the non-PCV-13 serotypes. Specifically, this increase was observed at the age of 0-4 years old (29.9% vs 70.1%) and 5-9 years of age (33.3% vs 66.6%) for the PCV-13 and non-PCV-13 serotypes respectively.

A high variation among the serotypes was observed in all age groups as 30 serotypes were detected. The most predominant serotypes in children 0-4 years old were 15B/C (11.7%) and 24F/40 (13.0%) followed by 19A, 12F, 35F/47F, 8, 10A, 21 and 23A. Among the 21 patients 5-9 years old, serotype 3 was predominant (4/21; 19%), followed by 23A, 23B and 15B/C. The persistence of serotypes 3 and 19A were be related to their specific characteristics as they are the most prevalent among the vaccine failure cases.

Conclusions/Learning Points:

Close monitoring and continuous surveillance of evolving serotypes is of high importance during the post PCV-13 era and crucial for the evaluation of the overall impact of pneumococcal vaccination programs and for designing future strategies.