Long COVID-19 (LC) patients experience a number of chronic idiopathic symptoms that are highly similar to those of post-viral myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). We have therefore performed a systematic review and meta-analysis to determine the proportion of LC patients that satisfy ME/CFS diagnostic criteria.

Clinical studies published between January 2020 and May 2023 were identified using the PubMed, Web of Science, Embase and CINAHL databases. Publication inclusion/exclusion criteria were formulated using the global CoCoPop framework. Data were pooled using a random-effects model with a restricted maximum-likelihood estimator. Study quality was assessed using the Joanna Briggs Institute critical assessment tool.

We identified 13 eligible studies that reported a total of 1973 LC patients. Our meta-analysis indicated that 51% (95% CI, 42%−60%) of LC patients satisfied ME/CFS diagnostic criteria, with fatigue, sleep disruption, and muscle/joint pain being the most common symptoms. Importantly, LC patients also experienced the ME/CFS hallmark symptom, post-exertional malaise.

Our study not only demonstrates that LC patients exhibit similar symptom clusters to ME/CFS, but that approximately half of LC patients satisfy a diagnosis of ME/CFS. Our findings suggest that current ME/CFS criteria could be adapted to the identification of a subset of LC patients that may facilitate the standardised diagnosis, management and the recruitment for clinical studies in the future.