A new study has shown that more than three quarters of Covid 19 patients have at least one persistent symptom six months after initially feeling unwell.
The study looked at the long-term effects of the coronavirus on people admitted to hospital in Wuhan, China, and found that the most common persistent symptom in 63% of patients is fatigue or muscle weakness.
Patients also have frequent sleep disorders (26%), and anxiety or depression were reported in 23% of patients, according to the study.
The researchers found that patients who were critically ill in the hospital were more likely to have compromised lung function and chest imaging abnormalities that could indicate organ damage, six months after symptoms began.
The study, published in The Lancet, found that in six patients whose immune response was tested at the time of infection, levels of neutralizing antibodies decreased by more than half (52.5%) after six months.
The researchers suspect that this raises concerns about the possibility of re-infection with the virus.
Professor Bin Cao of the National Center for Respiratory Medicine, China-Japan Friendship Hospital and Capital Medical University said, “With Covid-19 such a new disease, we are only just beginning to understand some of its long-term effects on patients’ health.
“Our analysis shows that most patients continue to live with at least some of the effects of the virus after leaving the hospital, and shows that care is required after discharge, especially for those with severe infections.
“Our work also underscores the importance of conducting longer follow-up studies in larger populations to understand the full range of effects Covid-19 can have on humans.”
The new study included 1,733 Covid-19 patients with a mean age of 57 who were discharged from Jinyintan Hospital in Wuhan between January 7 and May 29 last year.
Follow-up visits were conducted from June 16 to September 3, 2020, and the mean follow-up time was 186 days.
All patients were interviewed face-to-face using questionnaires to assess their symptoms and health-related quality of life.
They also underwent physical exams, laboratory tests, and a six-minute walk test to measure patient endurance.
In addition, 94 patients whose blood antibody levels were recorded at the peak of the infection as part of another study received a follow-up test.
At follow-up, 76% of patients (1,265 / 1,655) reported at least one persistent symptom.
Fatigue or muscle weakness was reported by 63% (1,038 / 1,655), while 26% (437 / 1,655) had difficulty sleeping and 23% (367 / 1,733) had anxiety or depression.
Of the 390 patients who underwent additional tests, 349 completed the pulmonary function test.
Patients with more severe disease often had decreased lung function, with 56% (48/86) of patients in severity five to six – who needed ventilation – experienced decreased oxygen flow from the lungs to the bloodstream.
For patients on the severity scale four – who needed oxygen therapy – and in patients on the severity scale three (who did not need oxygen therapy) the numbers were 29% (48/165) and 22% (18/83), respectively.
Patients with more severe disease performed worse on the six-minute walk test, with 29% of patients with severity five to six walking less than the lower limit of the normal range, compared with 24% for patients on scale three and 22% for patients on scale four.
The researchers also found that some patients developed kidney problems after being discharged.
Tests showed that 13% (107/822) of patients whose kidney function was normal in the hospital had decreased kidney function at follow-up.
The researchers say that because the number of participants with antibody test results was limited in both the acute phase and follow-up, larger samples will be needed in the future to clarify how antibody levels to the virus change over time .
They add that more work is needed to compare differences in outcomes between inpatients and outpatients, as patients with mild Covid-19 symptoms who remained in Fangcang makeshift animal shelter hospitals were not included in the study.