Fatigue, including postexertion malaise and impaired daily function and mobility, is the most common symptom of long COVID,8-10,14 reported in 28% to 98%14 of patients after initial COVID-19. This fatigue is more than simply being tired: Patients describe profound exhaustion, in which fatigue is out of proportion to exertion. Fatigue and myalgia are commonly reported among patients with impaired hepatic and pulmonary function as a consequence of long COVID.13 Patients often report that even minor activities result in decreased attention, focus, and energy, for many hours or days afterward. Fatigue has been reported to persist from 2.5 months to as long as 6 months after initial infection or hospitalization.9,16
Postviral fatigue has been seen in other viral outbreaks and seems to share characteristics with myalgic encephalomyelitis/chronic fatigue syndrome, or ME/CFS, which itself has historically been stigmatized and poorly understood.17 Long COVID fatigue might be more common among women and patients who have an existing diagnosis of depression and antidepressant use,10,11,16,18 although the mechanism of this relationship is unclear. Potential mechanisms include damage from systemic inflammation to metabolism in the frontal lobe and cerebellum19 and direct infection by SARS-CoV-2 in skeletal muscle.20 Townsend and colleagues16 found no relationship between long COVID fatigue and markers of inflammation (leukocyte, neutrophil, and lymphocyte counts; the neutrophil-to-lymphocyte ratio; lactate dehydrogenase; C-reactive protein; serum interleukin-6; and soluble CD25).
Neuropsychiatric symptoms are also common in long COVID and can have a significant impact on patients’ quality of life. Studies have reported poor sleep quality or insomnia (38% to 90%), headache (17% to 91.2%), speech and language problems (48% to 50%), confusion (20%), dementia (28.6%), difficulty concentrating (1.9% to 27%), and memory loss or cognitive impairment (5.4% to 73%).9,10,14,15 For some patients, these symptoms persisted for ≥ 6 months, making it difficult for those affected to return to work.9
Isolation and loneliness, a common situation for patients with COVID-19, can have long-term effects on mental health.21 The COVID-19 pandemic itself has had a negative effect on behavioral health, including depression (4.3% to 25% of patients), anxiety (1.9% to 46%), obsessive compulsive disorder (4.9% to 20%), and posttraumatic stress disorder (29%).22 The persistence of symptoms of long COVID has resulted in a great deal of frustration, fear, and confusion for those affected—some of whom report a loss of trust in their community health care providers to address their ongoing struggles.23 Such loss can be accompanied by a reported increase in feelings of anxiety and changes to perceptions of self (ie, “how I used to be” in contrast to “how I am now”).23 These neuropsychiatric symptoms, including mental health conditions, appear to be more common among older adults.4
Other neurologic deficits found in long COVID include olfactory disorders (9% to 27% of patients), altered taste (5% to 18%), numbness or tingling sensations (6%), blurred vision (17.1%), and tinnitus (16.%).14 Dizziness (2.6% to 6%) and lightheadedness or presyncope (7%) have also been reported, although these symptoms appear to be less common than other neurocognitive effects.14
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