Pre-vaccination carriage prevalence of Streptococcus pneumoniae serotypes among internally displaced people in Somaliland

Populations affected by humanitarian crises likely experience high burdens of pneumococcal disease. Streptococcus pneumoniae carriage estimates are essential to understand pneumococcal transmission dynamics and the potential impact of pneumococcal conjugate vaccines (PCV). This paper presents only the second pneumococcal carriage estimates for a displaced population.

Nasopharyngeal swab samples were collected from internally displaced people (IDP) living in Digaale, Somaliland where PCV has not been implemented. The study found that pneumococcal carriage prevalence was 36% in all ages, and 70% in children under 5. The three most common serotypes were vaccine serotypes 6B, 19F, and 23. There was some evidence that pneumococcal carriage was associated with recent respiratory symptoms, the total number of physical contacts made, and with malnutrition in children under 5. Through linking with a nested contact survey the study projected that pneumococcal exposure of children under 2 was predominantly due to contact with children aged 2-5 and 6-14.

These findings suggest considerable potential for direct and indirect protection against pneumococcal disease in Digaale through PCV use in children and potentially adolescents.