Objectives Long COVID following SARS-CoV-2 and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) following infectious mononucleosis (IM) are examples of post-infectious chronic illnesses. Behavioral and pathophysiological underpinnings of both ME/CFS following IM and Long COVID are not well understood. Methods We studied ME/CFS development following IM in a diverse group of college students who were enrolled before the onset of IM. We categorized those meeting either moderate or severe ME/CFS criteria. We subsequently recruited a matched sample of those infected with SARS-CoV-2, some of whom recovered and others of whom developed Long COVID. We compared and contrasted ME/CFS and Long COVID following IM and SARS-CoV-2 infection in terms of somatic symptoms, coping strategies, depression and anxiety symptoms, and functional status. Results In general, the Long COVID group's symptom burden was less than that of the Severe ME/CFS group but more than that of the Moderate ME/CFS group. Discussion These findings may allow investigators a better understanding of these post-viral illness pathophysiologies.
Jason et al. (2026) studied this question.