SIGLEC1 and COVID-19: The failure to subsequently regulate and dampen this innate response resulted in unchecked host immune responses and collateral tissue damage for C1Q low macrophages, while C1Q high macrophages have elevated complement cascade activation (for example, LGALS3BP56) and express genes correlating with mild rather than severe COVID-19 symptoms (for example, SIGLEC1, ref. 57).