How long do Covid-19 symptoms linger? People suffer from at least one of them even after 6 months, finds study
Millions of people globally have been infected with Covid-19 and many have recovered. But questions remain about what recovery implies, what are the long-lasting health impacts, and how long are the physical after-effects of the disease. A new analysis throws some light on these critical questions.
More than three quarters or 76% of patients hospitalized with coronavirus were struggling with at least one symptom six months after falling sick, found researchers. While people were troubled with fatigue or muscle weakness (63% of patients), which was the most common symptom, sleep difficulties (26%), as well as anxiety or depression (23%), were also frequently reported by survivors.
Patients who were severely ill in the hospital more often had impaired lung function and abnormalities detected in chest imaging — which could indicate organ damage — six months after symptom onset. Follow-up blood antibody tests from 94 patients after six months revealed that levels of neutralizing antibodies were 52.5% lower than at the height of infection. According to authors, this raises concerns about the possibility of Covid-19 re-infection.
The findings, published in The Lancet, are a stark reminder that death is not the only thing to fear from the virus. The team has called for post-discharge care and further research in a larger population.
“Because Covid-19 is such a new disease, we are only beginning to understand some of its long-term effects on patients’ health. Our analysis indicates that most patients continue to live with at least some of the effects of the virus after leaving the hospital and highlights a need for post-discharge care, particularly for those who experience severe infections," suggests Professor Bin Cao, from National Center for Respiratory Medicine, China-Japan Friendship Hospital and Capital Medical University.
Cao adds, "Our work also underscores the importance of conducting longer follow-up studies in larger populations to understand the full spectrum of effects that Covid-19 can have on people.”
What did investigators find?
The authors say that follow-up studies that have been conducted so far have looked only at a small number of cases over a short follow-up period, typically around three months after discharge.
A July estimate from the Centers for Disease Control and Prevention (CDC), for example, suggests that 35% had not returned to their usual state of health when interviewed 2-3 weeks after testing. Among persons aged 18-34 years with no chronic medical conditions, one in five had not returned to their usual state of health, it notes. A recent report found that 1 in 10 respondents testing positive for coronavirus exhibit symptoms for 12 weeks or longer.
Accordingly, the new analysis looked at 1,733 coronavirus patients who were discharged from Jin Yin-tan Hospital in Wuhan, China, between January 7 and May 29, 2020. Patients had a median age of 57 years. Follow-up visits were done from June 16 to September 3, 2020, and the median follow-up time was 186 days.
All patients were interviewed face-to-face using questionnaires to evaluate their symptoms and health-related quality of life. They also underwent physical examinations, lab tests and a six-minute walking test to gauge patients’ endurance levels. 390 patients had further tests, including an assessment of their lung function. Besides this, 94 patients whose blood antibody levels were recorded at the height of the infection as part of another trial received a follow-up test.
At follow-up, 1,265 out of 1,655 patients reported at least one ongoing symptom. Fatigue or muscle weakness was reported by 1,038 out of 1,655, while 437 had sleep difficulties and 367 experienced anxiety or depression.
Of the 390 patients who underwent additional testing, 349 completed the lung function test; 41 were unable to complete the test due to poor compliance. Patients with more severe illness commonly had reduced lung function, with 56% (48 out of 86) of those at severity scale 5-6 (who required ventilation) experiencing diffusion impairment — which means a reduced flow of oxygen from the lungs to the bloodstream.
For patients at severity scale 4 (who required oxygen therapy) and those at scale 3 (who did not require oxygen therapy) the figures were 29% (48 out of 165) and 22% (18 out of 83), respectively.
Patients with more severe disease performed worse in the six-minute walking test, which measures the distance covered in six minutes. An estimated 29% of those at severity scale 5-6 walking less than the lower limit of the normal range, compared with 24% for those at scale 3 and 22% for scale 4.
Some patients went on to develop kidney problems post-discharge. Lab tests revealed that 13% (107 out of 822) of patients whose kidney function was normal while in hospital had reduced kidney function in the follow-up.
According to investigators, impaired lung function and exercise capacity observed in the study cannot be directly attributed to Covid-19 as baseline data for these are unavailable. It was also not possible to determine if symptoms reported during follow-up were persistent following the infection, worsened after recovery or occurred post-discharge.
Writing in a linked comment, experts say that while the findings offer a comprehensive clinical picture of the aftermath of Covid-19 in hospitalized patients, only 4% were admitted to an intensive care unit (ICU), rendering the information about the long-term consequences in this particular cohort inconclusive.
“Nonetheless, previous research on patient outcomes after ICU stays suggests that several Covid-19 patients who were critically ill while hospitalized will subsequently face impairments regarding their cognitive and mental health and/or physical function far beyond their hospital discharge,” note Monica Cortinovis, Norberto Perico and Giuseppe Remuzzi from the Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Italy, who were not involved in the analysis.