Over three quarters of COVID-19 patients still exhibit at least one ongoing symptom, most commonly fatigue and muscle weakness, six months after they began showing symptoms, a new cohort study which was published in The Lancet medical journal on Friday found.
The study looked at the long-term effects of COVID-19 on 1,733 patients who were hospitalized in Wuhan, China, which was the disease's first epicenter.
During the study, all patients underwent face-to-face interviews to evaluate their symptoms and health-related quality of life, as well as physical exams, lab tests and a six-minute walking test to gauge patients' endurance levels.
In addition, 390 patients underwent further tests, including an assessment of lung function, and 94 patients whose blood antibody levels were recorded at the height of the infection as part of another trial received a follow-up test.
It found that of the 76% of patients who experienced at least one continued symptom, 63% experienced fatigue or muscle weakness, 26% experienced sleep difficulties, 23% reported anxiety or depression.
The study also found that patients who had been severely ill during their hospitalization were more likely to have impaired lung function and abnormalities detected in chest imaging six months later, a possible indication of permanent organ damage.
According to the data, 56% of patients who required intubation, experienced impaired oxygen flow from their lungs to the bloodstream, and 29% of formerly intubated patients struggled with the six-minute walking test.
In addition, 94 patients whose immune response was tested at the peak of their infection saw the levels of neutralizing antibodies in their blood fall 52.5%, raising concerns that reinfection may not only be possible through virus strain mutation, but that patients could also be reinfected with the same strain they had previously overcome.
The study also found that kidney problems may also arise after COVID-19 infection, with 13% of patients whose kidney function was normal during hospitalization, seeing reduced kidney function six months later.
"Because COVID-19 is such a new disease, we are only beginning to understand some of its long-term effects on patients' health," said Professor Bin Cao, from the National Center for Respiratory Medicine, China-Japan Friendship Hospital and Capital Medical University.
"Our analysis indicates that most patients continue to live with at least some of the effects of the virus after leaving hospital, and highlights a need for post-discharge care, particularly for those who experience severe infections," Prof. Cao said.
"Our work also underscores the importance of conducting longer follow-up studies in larger populations in order to understand the full spectrum of effects that COVID-19 can have on people," he added.