Monitoring the introduction of pneumococcal conjugate vaccines into West Africa: design and implementation of a population-based surveillance system.
Mackenzie GA, Plumb ID, Sambou S, Saha D, Uchendu U, Akinsola B, Ikumapayi UN, Baldeh I, Usuf E, Touray K, et al. PLoS Med. 2012 Jan; 9(1):e1001161. Epub 2012 Jan 17.