The recombinant S1 subunit of the SARS-CoV-2 Spike protein activated in vitro human peripheral blood monocytes to release several cytokines (e.g., IL-6, IL-1β, TNF-α) and chemokines (e.g., CXCL10/IP-10, CCL3/MIP-1α, CCL4/MIP-1β) linked to COVID-19 (224). Here, CXCL10 is linked to COVID-19.