Long after the global lockdown is lifted and the pandemic has receded, health services in many places may still be treating vast numbers of long-term victims of the coronavirus.
Worrying evidence from early studies of patients with Covid-19 is emerging to suggest the infection may leave behind debilitating conditions ranging from sensory loss to heart and lung damage.
These might afflict only a small proportion of sufferers. But so vast are the numbers infected that the long-term afflicted may be in the millions.
Already coronavirus is being reported to cause lasting injuries to lungs and hearts, for example. But history suggests there may be other consequences.
After the 1918 Spanish flu pandemic, in which up to half a billion people are thought to have been infected, many who survived experienced persistent lethargy and depression, says Laura Spinney, author of Pale Rider: The Spanish Flu Of 1918 And How It Changed The World
'The virus affected the entire constitution,' she says. 'People also reported dizziness, insomnia, loss of hearing or smell, and blurred vision.'
And some believe the Covid-19 outbreak will lead to a similar explosion in post-viral malaise and depression.
There is a precedent with other epidemics. 'Psychiatric and neurological complications had been reported during the Sars epidemic in 2003,' the Italian Society of Neurology recently warned.
'Apart from depressive mood alterations, anxiety disorder and suicidal ideas, cases of visual and auditory hallucinations, behavioural disturbances, delusions of persecution and disorientation have been reported.'
In 2011, Canadian researchers reported on a condition they called chronic post-Sars syndrome in 22 patients, in the journal BMC Neurology. All the patients suffered persistent fatigue, pain, weakness and depression.
The link between respiratory viruses and mood disorders was supported by infectious disease experts at the Royal Free Hospital and University College London Medical School writing in the journal Brain, Behavior and Immunity in 2016.
They found that people who had a flu infection in the previous 30 to 180 days had a 57 per cent higher risk of developing depression, compared with people who had not contracted flu.
Any viral infection, from mumps to glandular fever or flu, can trigger post-viral syndrome, leading to persistent weakness and exhaustion. Symptoms can include headaches, aches and pains, stiff joints, swollen glands and trouble concentrating and can last weeks or even months.
Quite why these symptoms persist is unclear, but it may be due to the virus triggering inflammation, or the lingering presence of the virus itself.
Covid-19 may lead to other long-term problems, too. Six in ten people who have tested positive for it say they have lost their sense of smell and of taste — a condition called anosmia.
The loss may be temporary, but British evidence suggests that in many cases it may be permanent — a condition called post-viral olfactory loss (PVOL).
Carl Philpott, a professor of rhinology and olfactology at the University of East Anglia, told Good Health: 'It is very reasonable to think that Covid-19 may cause permanent smell and taste loss.'
PVOL is already seen after respiratory infections, such as flu, when 'the infection causes fine hair-like endings of the odour-receptor cells inside the nose to fall off, so the cells are no longer able to pick up odour molecules from the nose', says Professor Philpott.
'However, with Covid-19, newly published reports suggest that the virus is damaging cells in the lining of the nose that support the receptor cells. It may be doing both forms of damage.
'Smell loss might seem trivial but it isn't to those who suffer it,' he warns. 'Many feel isolated from normal life — which explains why more than 60 per cent report feeling stressed and depressed.
'An inability to smell can affect everything from enjoying countryside walks to personal relationships,' he adds. 'Our sense of smell is directly related to our ability to taste, so sufferers no longer share the joys of eating and drinking with friends and family. Around a third lose interest in food. Others resort to living on unhealthy takeaway curries, so they can experience some level of sensation.'
NHS says smell training, which involves sniffing scented oils daily to stimulate the olfactory nerves that detect odours, may coax the sense to return.
Meanwhile, as many as one in four people will have a post-viral cough that can persist for up to ten weeks after their bodies are clear of coronavirus.
Ron Eccles, an emeritus professor who established the Common Cold Centre at Cardiff University, says: 'Post-viral inflammation of the airway means this debilitating symptom can linger after the initial infection has gone.'
Far more concerning are reports that Covid-19 infection may cause pulmonary fibrosis, scarring of the lung tissue that affects breathing.
Last month, researchers at George Washington University Hospital in the U.S. posted images online showing serious inflammation on the lungs of a 59-year-old patient with Covid-19 symptoms.
Keith Mortman, head of the hospital's thoracic surgery department, warned: 'When this inflammation is reduced and the infection is cleared, it leaves scars on the lungs. This may deteriorate breathing capacity in the future.'
In Hong Kong, a study of 12 people who recovered from coronavirus reports that three cannot walk briskly without becoming breathless because of lung damage.
Owen Zeng, head of the infectious disease centre at Princess Margaret Hospital, has predicted some Covid-19 patients may have a 20 to 30 per cent reduction in lung function.
He is advising discharged patients to do exercises that stimulate the cardiovascular system, such as swimming, in the hope that this may help their lungs to recover gradually.
Cardiovascular experts, meanwhile, are concerned that Covid-19 infection may cause lasting harm to hearts — even in people with no previous underlying heart problems.
A report in the journal JAMA Cardiology by the University of Texas in the U.S. warned that coronavirus can cause inflammation of the heart.
This can lead to myocarditis, where inflammation weakens the organ and creates scar tissue that forces it to work harder to circulate blood and oxygen. Damage can be permanent.
Scarring from coronavirus can also cause heart rhythm problems by inhibiting the healthy movement of the heart muscle, according to the Texas cardiologists. Symptoms can range from a minor inconvenience to a potentially fatal heart attack.
We know the cardiac injury risk is there from coronaviruses, no matter if you had prior heart disease or not,' said Mr Mohammad Madjid, an assistant professor of cardiology at the University of Texas.
Just last month, a study of 416 adults by the University of Wuhan — the city in China where the coronavirus outbreak began — reported in Jama Cardiology that one in five hospitalised Covid-19 patients had lasting heart damage.
Such evidence suggests NHS may have to provide services and support for coronavirus survivors who may have developed new heart and lung conditions.
Kenneth Tyler, a professor of neurology at Colorado University School of Medicine in the U.S. is also predicting that the epidemic could leave a legacy of neurological diseases caused by damage to brain tissue and nerves.
As Tyler warns, healthcare specialists must be made available and funded to address the health damage that Covid-19 may leave in its wake.
'This is the Wild West,' he says. 'We may find things that we hadn't expected. And then we have to sort them out.'
Daily Mail
