People are destroyed by this. They never expected it to be long term

The lives of people who were previously healthy have changed so dramatically after what seemed to have been a mild to moderate illness. They don't know how to adjust to this, and just want their lives back.

As eight months have passed since the start of the coronavirus pandemic and we learn more about Covid-19, it is becoming increasingly evident that even mild cases can have distressing and long-lasting effects.

The lasting effects do not seem to be related to the severity of the initial stages of the infection; even mild cases can present with long lasting and debilitating long term symptoms.

When the WHO announced a pandemic in early March, the prevailing view was that we were dealing with a severe respiratory infection that had symptoms similar to flu, and that while some people would develop pneumonia and need breathing support, most would experience a mild to moderate illness characterised by a cough, fever and shortness of breath, which with good treatment could be over in several weeks.

Soon, though, scientific collaboration and reporting between the countries hit by the virus revealed that there were other symptoms, including a variety of skin lesions that presented at various stages of the disease. This was looking as if the virus affected more body systems, and over a longer period of time than originally thought. Indeed, hardly anyone’s symptoms are the same the whole way through.

The Covid Symptom Tracker app launched on 23 March – the start of the UK’s own lockdown, and soon revealed lack of smell coming up as the top symptom, present in 60 per cent of people who had positive tests. This is higher than fever or cough, in predictive terms, because some of those who tested negative for the coronavirus also had fever or cough. Studies in China and Italy also found loss of smell and taste to be quite common in people with Covid-19. As a result, loss of smell and taste are now recognised as a key symptom by several health bodies including the NHS.

Other predictors currently being investigated are severe muscle pain, which seems to differ from the general aches and pains you get with the flu, and loss of appetite, which may be connected to the loss of taste or smell.

The list of unexpected symptoms doesn’t stop there. Gastrointestinal problems, such as diarrhoea, nausea and vomiting, and neurological symptoms ranging from headaches and dizziness to seizures and hallucinations. There have also been reports of Covid-19 patients being discharged from hospital, only to return several weeks later with a deep vein thrombosis or blood clot on the lung.

Then there is the extreme fatigue. Paul Garner, who had to stop working after coming down with Covid-19 in mid-March, likens the feeling to being hit over the head with a cricket bat. “Calling it post-viral fatigue isn’t helpful because the fatigue has been there from day one, and runs alongside some quite nasty, life-threatening conditions,” he says. “It also implies we know what’s happening and that the virus has gone – but we don’t know any of this stuff really.” The weird thing with Covid-19 is how it sort of goes away, and you feel a bit muggy and a little bit drained and then you feel a bit better and then, whack, it comes at you again from another direction.

Inflammation in the body may persist long after SARS-CoV-2 has been cleared from the body. Another source of prolonged inflammation could be the gut. Cells lining the gastrointestinal tract have a receptor called ACE2 on their surface – the same receptor that SARS-CoV-2 uses to gain access to lung cells – which suggests they could become infected and inflamed. Researchers in Hong Kong have also identified an altered gut bacteria profile in people infected with the virus, characterised by large numbers of harmful bacteria and the depletion of beneficial ones. These changes persisted even after the virus had been cleared from the body. If the bacteria in your gut have not recovered, you may have some lasting fatigue, discomfort or loss of appetite, and it may also make you more susceptible to other infections.

One question raised by many of those experiencing persistent symptoms is whether they are still infectious. Kim Clarke, who lives in Surrey, UK, has repeatedly tested positive for the coronavirus in her blood since losing her sense of smell on 1 April. She has been caring for her three children at home, despite severe and ongoing breathlessness, fatigue and headaches. “They’re saying, because I’ve had the virus for so long, that I can’t still be infectious, but I don’t think anyone knows anything really,” she says. “At least it helps explain why I still feel so rough. I can’t leave the house because I can’t walk, I can’t breathe.”

Until now, much of the response to Covid-19 has been about preventing deaths, but hospitals are beginning to establish clinics to follow-up the survivors – including those who are still ill.