ME (Myalgic Encephalomyelitis) is a severe, immune-mediated illness often triggered by viral infection. Until the emergence of SARS-CoV-2, causing COVID-19, anyone who fit the diagnostic criteria for ME/CFS (often referred to as chronic fatigue syndrome, CFS) would be diagnosed with ME/CFS no matter whether their illness was triggered by viral or bacterial infections, physical or emotional trauma, surgery, childbirth, or allergic reaction.