Spatial Distribution of Invasive Pneumococcal Serotypes in West Africa: A Retrospective Analysis to Inform Immunization in Persons with Sickle Cell Disease

Background: Susceptibility to invasive pneumococcal disease (IPD) is high in children with sickle cell disease (SCD). National guidelines in many countries recommend a combined schedule of 13-valent pneumococcal conjugate vaccine (PCV13) beginning after birth followed by the 23-valent polysaccharide vaccine (PPSV23) beginning at age 2 years. In Africa, where the burden of SCD is greatest, PPSV23 is generally unavailable and not routinely administered to children with SCD. To help inform optimal immunization regimens for children with SCD in West Africa, we sought to determine the prevalence and spatial distribution of IPD in the region. We focused specifically on the 24 combined pneumococcus strains covered by PCV13 (serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) and PPSV23 (serotypes 1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F). This analysis also explored the epidemiology of IPD-associated serotypes after the introduction of routine PCV13 immunization in countries in West Africa.