Sickle cell disease (SCD) is a group of inherited disorders caused by mutations in HBB, which encodes haemoglobin subunit β. The incidence is estimated to be between 300,000 and 400,000 neonates globally each year, the majority in sub-Saharan Africa. Haemoglobin molecules that include mutant sickle β-globin subunits can polymerize; erythrocytes that contain mostly haemoglobin polymers assume a sickled form and are prone to haemolysis. Other pathophysiological mechanisms that contribute to the SCD phenotype are vaso-occlusion and activation of the immune system. SCD is characterized by a remarkable phenotypic complexity. Common acute complications are acute pain events, acute chest syndrome and stroke; chronic complications (including chronic kidney disease) can damage all organs. Hydroxycarbamide, blood transfusions and haematopoietic stem cell transplantation can reduce the severity of the disease. Early diagnosis is crucial to improve survival, and universal newborn screening programmes have been implemented in some countries but are challenging in low-income, high-burden settings.

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The potential for continued penicillin prophylaxis to contribute to the development of multiply resistant pneumococci should be considered before continuing penicillin prophylaxis in children with sickle cell anemia who are older than 5 years of age. Added to the published data from PROPS II, which demonstrated no apparent advantage to continue prophylaxis, the data support the conclusion that, for children with no history of invasive pneumococcal disease, consideration should be given to discontinue prophylactic penicillin after their fifth birthday.