We observed significant elevation of a wide range of cytokines and chemokines including IL-6, TNF-α, IL-10, IFN-γ, IL-2, IL-4, IL-15, eotaxin, eotaxin3, IL-8, IP-10, MIP-1α, MCP-1, and MIP-1β in plasma specimens of COVID-19 patients (both mild/moderate and severe) versus HCs (Fig. 2A to C). Here, IL15 is linked to COVID-19.