This mirrors recent immunophenotyping work by Hawerkamp et al., who used principal component analysis of 20 cytokines to define a pro-inflammatory cytokine signature (dominated by IL-1β, IL-2, IL-6, IL-10, IL-33, TNF-α, IP-10, and G-CSF) that independently predicted severe COVID-19, invasive mechanical ventilation (aOR 1.61), and mortality (aOR 1.57) per SD increase in the signature score [21]. Here, IL2 is linked to COVID-19.