IL4 and malaria: The subgroup analysis of study designs revealed no difference in IL-4 levels between severe and uncomplicated malaria between case–control studies (pooled MD −4.86 pg/mL, 95% CI −9.89 to 0.17 pg/mL, I2 95.74%, four studies), prospective observational studies (pooled MD 3.25 pg/mL, 95% CI −0.18 to 6.68 pg/mL, I2 95.74%, three studies), and cross-sectional studies (pooled MD −80.67 pg/mL, 95% CI −238.84 to 77.5 pg/mL, I2 99.72%, two studies, Additional file 1: Fig. S1).