Document resource
While the number of fatal acute SARS-CoV-2 infections has declined since 2020, the proportion of these infections that result in persisting symptoms has not reduced significantly. 1 The continuity or development of new symptoms longer than 3 months after an acute SARS-CoV-2 infection is clinically defined as long covid.2 PEM, a hallmark and debilitating feature, is recognised as one of the most frequent manifestations of long covid and is present in ~80% of patients with the condition.3 PEM is a delayed exacerbation (or new onset) of symptoms after physical or cognitive activity above a patient- and time-dependent threshold, which may persist for days, weeks or months or even result in a permanent change in a patient’s baseline.2 The need to screen for PEM in suspected long covid before initiating a rehabilitation strategy has already been recognised by major health authorities, including the WHO, who heavily cautioned against graded exercise therapies for patients experiencing PEM.2