Explained: Why impact of 'long Covid' could outlast the pandemic

Millions of people who have gotten Covid-19 and survived are finding that a full recovery can be frustratingly elusive. Weeks and months after seemingly recovering from even a mild case, many patients still confront a wide range of health problems. As researchers try to measure the duration and depth of what’s being called “long Covid”, the scale of the pandemic means that Covid’s disabling effects — as well as the economic pain and drain on health resources — could persist well after the contagion ends. 

What are the ailments?

Fatigue, shortness of breath, chest pain, joint aches and cognitive disturbances including “brain fog” are commonly described problems that emerge or linger four weeks or more after an infection with SARS-CoV-2, the coronavirus that causes Covid-19. The severity can range from annoying to incapacitating. Specific organ dysfunction also has been reported involving primarily the heart, lungs and brain, even among those who had no noticeable symptoms during the acute phase. 

How prevalent is it?

Although data are emerging, researchers haven’t studied enough patients over a long enough period of time to gauge the full range of long-term effects — what doctors call the post-acute sequelae — what proportion of patients will suffer from them, or for how long. Early findings and the demand for specialised clinics to help survivors deal with scarred lungs, chronic heart damage, fatigue and other conditions indicate a significant prevalence. A large Danish study of people whose infections didn’t require hospitalisation found the absolute risk of severe, post-acute complications was low, but also noted increases in general practitioner and outpatient hospital visits, which could indicate lingering symptoms.

What are the estimates?

The UK’s Office of National Statistics estim­a­ted in December that, among people who have tested positive for Covid-19, about one in five exhibit symptoms for five weeks or longer, and about one in 10 have symptoms for 12 weeks or longer. A separate UK study found seven in 10 patients had not fully recovered five months after discharge. A small study from the University of Washington reported persistent symptoms for as long as nine months after an acute bout of Covid-19. A much larger study involving almost 240,000 Covid-19 patients found one in three received a neurological or psychiatric diagnosis within six months of infection.

Is Covid-19 definitely to blame for these symptoms?

Not necessarily. A large study based on data from a US health plan published in The BMJ in mid-May found that 14 per cent of people infected with SARS-CoV-2 developed one or more related complications requiring medical care beyond the acute phase of the illness — but so did 9 per cent of the people in an unaffected control group. Some conditions in Covid-19 survivors might occur by chance or be triggered by pandemic-induced stress and anxiety. A study of health-care workers at a Swedish hospital compared persistent symptoms among those who had recovered from mild Covid-19 at least 8 months before, and those who never caught the coronavirus. Among those who’d been infected, 8 per cent reported lingering symptoms causing moderate-to-marked disruptions of their work life, compared with 4 per cent in the non-infected group. Uncertainties about conditions attributable to Covid-19 have sometimes led to what patients describe as medical gaslighting by health professionals who don’t take their complaints seriously, especially if the patient is a woman.

Do other viruses cause prolonged illness?

Yes. So-called post-viral syndromes occur after many viral infections, including the common cold, influenza, HIV, infectious mononucleosis, measles and hepatitis B. Diabetes and other long-term consequences were observed in survivors of severe acute respiratory syndrome (SARS), which is caused by coronavirus related to SARS-CoV-2. A Canadian study identified 21 healthcare workers from Toronto who had post-viral symptoms for as long as three years after catching SARS in 2003 and were unable to return to their usual work. Some people who were hospitalised with SARS in Hong Kong still had impaired lung function two years later, a study of 55 patients published in 2010 found. Still, it’s not known yet whether the lessons of SARS are applicable to Covid-19.