Impact of pneumococcal conjugate vaccines on S. pneumoniae carriage in infant and toddlers with acute otitis media in Morocco - 13/10/26
, Abdellatif Loudghiri e, Mostafa Katfy a, b, Fatiha Raji f, Maha Soussi Abdallaoui a, bAbstract |
Background |
Streptococcus pneumoniae remains a major cause of pediatric infections despite pneumococcal conjugate vaccines (PCVs). In Morocco, the concurrent use of PCV10 and PCV13 offers a unique opportunity to evaluate their impact on nasopharyngeal carriage and serotype distribution.
Objective |
To describe pneumococcal serotypes in the nasopharyngeal flora of young children with acute otitis media (AOM) in Casablanca and to compare serotype distribution according to vaccination status.
Methods |
In this prospective, multicenter, cross-sectional study (2020–2024), children aged 6–36 months with AOM had a nasopharyngeal swab performed. Isolates were serotyped by Quellung reaction and PCR and classified as vaccine (VTs) or non-vaccine types (NVTs); Haemophilus influenzae isolates were serotyped by slide agglutination.
Results |
Of 442 children, 172 pneumococci were recovered (carriage rate of 38.9%), representing 18 serotypes. PCV10 serotypes accounted for 49.4% and additional PCV13 serotypes for 21.5%; the main non-PCV13 serotypes were 11 A, 15B, and 10 A. Theoretical coverage reached 73.8% for PCV15 and 92.4% for PCV20. Among 136 isolates tested, two were fully penicillin-resistant (MIC > 2 mg/L). Of 74 H. influenzae isolates, 10.8% were serotype b and 20.3% serotype f; β-lactamase production was found in 10.8%, and a BLNAR phenotype in six isolates (8.1%) .
Conclusion |
Persistent vaccine-type carriage alongside emerging non-vaccine serotypes indicates incomplete serotype replacement in Morocco. PCV13 provided broader coverage than PCV10, mainly through serotypes 19 A and 3. Most non-PCV13 serotypes were included in PCV20, supporting its potential integration into the national immunization program and continuous serotype surveillance.
Le texte complet de cet article est disponible en PDF.Highlights |
• | Unique vaccine setting: Morocco uses PCV10 in public sector, PCV13 private sector, enabling direct vaccine strategy comparison. |
• | Study population: Prospective study 2020–2024, 442 children aged 6–36 months with acute otitis media in Casablanca. |
• | Serotype findings: 172 pneumococcal isolates identified (39% carriage rate), with 19 distinct serotypes; PCV10 accounted for 49.4% and additional PCV13 serotypes for 21.5%. |
• | Coverage potential: Coverage 73.8% with PCV15, 96.5% with PCV20, showing broader protection of newer vaccines. |
• | Public health implication: Persistence of vaccine-type carriage and emergence of non-vaccine serotypes underscore incomplete replacement, supporting PCV20 introduction and continuous surveillance. |
Keywords : Streptococcus pneumoniae , Acute otitis media, Nasopharyngeal carriage, Pneumococcal conjugate vaccines, Serotype distribution
Plan
Vol 56 - N° 7
Article 105349- octobre 2026 Retour au numéro
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