Beyond IL-6, which remains indicative of severe cytokine release syndrome (CRS) at levels exceeding 1000 pg/mL, a multi-cytokine panel (IL-8, IL-10, IL-15, IFN-γ, TNF receptor p55) within 36 hours improved prediction of severe CRS. The gene discussed is CXCL8; the disease is congenital rubella syndrome.