ORs for severe malaria by HbAS, α⁺thalassemia, and Hp genotypes. Logistic regression models were used to determine ORs for risk of severe malaria by (A) Hb type (HbAS), α⁺thalassemia type, and Hp genotype. HbAA, αα/αα and Hp1-1 were the respective reference types with an OR for severe malaria of 1.0. (B) Hb type (HbAS) and α⁺thalassemia type stratified by Hp genotype. HbAA and Hp1-1 and αα/αα and Hp1-1 were the respective reference types with an OR for severe malaria of 1.0.