Serum IL-6 level≥0.7 pg/mL at eligibility and baseline assessment.Temporal Experience of Pleasure Scale anticipatory pleasure score≤41 (based on item numbers 1, 3, 7, 11, 12, 14, 15, 16, 17 and 8) and consummatory pleasure score≤36 (based on item numbers 2, 4, 5, 6, 8, 9, 10 and 13).Evidence of COVID-19 immunity required prior to infusion, confirmed before randomisation using evidence of vaccination and antibody titre test. The gene discussed is IL6; the disease is COVID-19.