IL7 and infection: In the second phase of infection, granulocyte colony-stimulating factor (G-CSF), inflammatory cytokines and biomarkers like interleukin IL-2, IL-6, IL-7, tumour necrosis factor-α (TNF-α) macrophage inflammatory protein 1-α, D-dimer, C-reactive protein (CRP) and ferritin are markedly elevated in patients who are critically ill (Ahmed and Hassan 2020).