Patients admitted to hospital with Covid-19 can suffer health problems even after a year, a study in Wuhan, China, the first region hit by the outbreak, has found.
Although most symptoms disappeared over the course of 12 months, around half of former patients still experienced at least one continuing symptom, most commonly fatigue or muscle weakness.
One in three patients still experienced shortness of breath.
The long Covid study, published in The Lancet, consisted of more than 1,200 patients who had been discharged from a hospital in Wuhan, China, between January and May 2020.
Researchers said that health systems must be prepared to offer long-term support and called for larger studies into the consequences of Covid, particularly for those who were admitted to intensive care units, as they are more likely to have problems months later.
Professor Bin Cao, of the National Centre for Respiratory Medicine at China-Japan Friendship Hospital, said: “Our study is the largest to date to assess the health outcomes of hospitalised Covid-19 survivors after 12 months of becoming ill. While most had made a good recovery, health problems persisted in some patients, especially those who had been critically ill during their hospital stay.
“Our findings suggest that recovery for some patients will take longer than one year, and this should be taken into account when planning delivery of healthcare services post-pandemic.”
The long-term effects of Covid-19 have been widely reported and are an increasing concern. A previous study by the same researchers showed that six months after an acute infection, about three quarters of patients had persistent health problems.
In the latest study, the proportion of patients still experiencing at least one symptom after one year fell from 68 per cent at six months to 49 per cent at 12 months.
This decrease was observed regardless of the severity of prior Covid-19 infection.
Compared with men, women were 1.4 times more likely to report fatigue or muscle weakness, twice as likely to report anxiety or depression and almost three times as likely to have lung diffusion impairment after 12 months.
The authors say these findings will be important for future research to better understand why Covid-19 symptoms persist in some people.
One of the study's authors, Lixue Huang of Capital Medical University and China-Japan Friendship Hospital, said: “The health status of matched people from the community who have never had Covid-19 gives us a useful comparison and can help us to understand the impact of the disease on survivors’ quality of life.”
Slightly more patients experienced anxiety or depression at one year than at six months (23 per cent at six months versus 26 per cent at 12 months).
Another researcher, Xiaoying Gu, of the Institute of Clinical Medical Sciences at the China-Japan Friendship Hospital, said: “We do not yet fully understand why psychiatric symptoms are slightly more common at one year than at six months in Covid-19 survivors.
“These could be caused by a biological process linked to the virus infection itself, or the body’s immune response to it. Or they could be linked to reduced social contact, loneliness, incomplete recovery of physical health or loss of employment associated with illness.”
A Lancet editorial published at the same time said: “As the Covid-19 pandemic continues, the need to understand and respond to long Covid is increasingly pressing.
“Symptoms such as persistent fatigue, breathlessness, brain fog, and depression could debilitate many millions of people globally. Yet very little is known about the condition,” the article states.
“With no proven treatments or even rehabilitation guidance, long Covid affects people’s ability to resume normal life and their capacity to work. The effect on society, from the increased healthcare burden and economic and productivity losses, is substantial.
“Long covid is a modern medical challenge of the first order.”