SARS-CoV-2 spike (S), membrane (M), and nucleocapsid (N) peptide–treated peripheral blood mononuclear cells (PBMCs) up-regulated IFN-γ but not interleukin-4 (IL-4) or IL-17, suggesting that a TH1 response was induced in COVID-19 (11, 12). Here, IL4 is linked to COVID-19.