Evaluating the Effectiveness of a Pneumococcal Immunisation Campaign in a Camp for Internally Displaced People

Summary

Pneumococcal conjugate vaccine (PCV) is used routinely worldwide as part of infant immunisations to prevent acquisition of S. pneumoniae, the aetiologic agent responsible for a large proportion of early childhood pneumonia and invasive disease. However, PCV has seen minimal uptake in populations affected by forced displacement and humanitarian crises, where the burden of pneumococcal disease is plausibly elevated. This study seeks to generate evidence on appropriate vaccination strategies for crisis-affected populations. The investigators plan to exhaustively vaccinate children aged between six months and four years in a camp for displaced persons outside Hargeisa, the capital of Somaliland. The study will deliver PCV in a campaign modality, so as to achieve both short- and long-term herd immunity effects that, the investigators hypothesise, will reduce population-wide nasopharyngeal S. pneumoniae transmission and thereby protect young children from pneumococcal disease. The study will adopt a quasi-experimental design, with baseline and post-intervention surveys to evaluate changes in pneumococcal carriage, complemented by safety assessment in children aged over 2 years, who fall outside of the WHO prequalification age range for the vaccine that will be used in this study (i.e. PNEUMOSIL) and for whom PCV safety data are scarce. In addition, we the study will also collect longitudinal data on incidence of pneumonia and antibiotic prescriptions in the camp.

Timeline

Start

2022-11-27

Primary completion

2025-01-18

Completion

2026-02-28

Publications

• Results van Zandvoort K, Hassan AI, Bobe MO, Pell CL, Ahmed MS, Ortika BD, Ibrahim S, Abdi MI, Karim MA, Eggo RM, Ali SY, Hinds J, Soleman SM, Cummings R, McGowan CR, Mulholland EK, Hergeye MA, Satzke C, Checchi F, Flasche S. Pre-vaccination carriage prevalence of Streptococcus pneumoniae serotypes among internally displaced people in Somaliland: a cross-sectional study. Pneumonia (Nathan). 2024 Dec 5;16(1):25. doi: 10.1186/s41479-024-00148-6.
• McGowan CR, van Zandvoort K, Ibrahim SA, Hassan AI, Ahmed AM, Magan MA, Muhumed MH, Mohamed MS, Cummings R, Ali SY, Mohamed MA, Saed MA, Karim MA, Hergeye MA, Flasche S, Checchi F. Safety and coverage of Pneumosil pneumococcal polysaccharide conjugate vaccine (10-valent PCV) in a camp for internally displaced persons in Somaliland. Vaccine. 2026 Jan 1;69:127991. doi: 10.1016/j.vaccine.2025.127991. Epub 2025 Nov 19.

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