Some days, digital marketer Hayley Forster just feels heavy and tired. But at other times, Forster, now 12 weeks post-Covid 19 – feels so exhausted she cannot, she says, lift her fingers.
Last week, Forster, who lives near Leeds with her husband Peter, a 38-year-old IT professional and their two girls, Annabel, 8 and Poppy, 6, tried a two-minute walk outside her home and ended up feeling so shattered she stayed in bed for the following weekend.
Forster's experience seems remarkably common. Anecdotally, many people who have had coronavirus are saying they are finding it leaves behind a residual tiredness which is difficult to overcome.
So persistent a symptom is post-viral fatigue that it has been included as a marker for the new Covidence UK study, which is looking into risk factors and long-term complications for Covid 19 as well as evaluating its impact on the UK population.
Adrian Martineau, Professor of Respiratory Infection and Immunity at Queen Mary University of London and lead investigator of the Covidence UK study, says: "It's crucial that we learn more about post-viral fatigue after Covid-19. We are already seeing this in clinic, and it is undoubtedly a significant issue for many people who have had the coronavirus."
In the US, Dr Gregory Poland, a vaccinologist at the Mayo Clinic in Minnesota, agrees that we need data.
"There has been no systematic review of this area yet," says Poland. "Although I am aware of one recently published study which suggests that stress on the body may for some patients uncover underlying conditions such as depression, anxiety, fatigue or PTSD."
Poland points out, "Post-infection fatigue is common to a lot of infections. Whether there's something else that would make it a bigger issue with Covid is as yet unknown. What we can say is that the receptors that the virus uses to infect the body are present in the brain, so I wouldn't be surprised if that were the case."
That won't be much comfort to Hayley Forster who is desperate to get back to be a hands-on mum to her girls.
Forster doesn't know how she caught the virus, but symptoms appeared just before lockdown. "I had dull chest pains and felt breathless – no fever or persistent cough so I wasn't worried."
As lockdown wore on, Forster developed a cough which made it hard for her to catch her breath. She started running a fever and the chest pain became constant.
Sent to a local testing centre by her GP, Forster was not offered a swab test but told she had pleurisy and to go home. The next day, she says, "I couldn't catch a breath and was told to go to A&E by the 111 operator."
At the hospital, she was given a chest X-ray and diagnosed with Covid as a result, with physicians saying that a swab test wasn't even needed by now.
But she was discharged and told to self-isolate with her family; the treatment was paracetamol and rest.
Four days later, Forster was back in hospital with unbearable chest pain. After testing for blood clots proved negative, she was again sent home.
"It was a scary experience," she says. "Everyone was worried."
Since then, Forster has improved; she is not as breathless, but the chest pain is intermittent.
Dr Ann Donnelly, a Derry-based GP, understands the problem as she too had the virus in April.
Donnelly tried to work remotely at first but after five days, admitted she needed rest. And although she has recovered now, her cough persisted.
Feeling worn out, she stresses, is entirely expected. "It is a normal reaction to any infection especially one which leads to a pronounced cytokine response."
Cytokines are a crucial part of the inflammatory process which your body releases when under threat from something like a virus. However, the body's white blood cells are overstimulated they may release too many cytokines at once (a cytokine storm) which can lead to symptoms ranging from aches and pain to fatigue.
Says Donnelly, "If you feel tired after the virus like this, it can mean that your immune response hasn't gone back to normal."
What she recommends as a treatment is the old-fashioned idea of a period of convalescence.
"You need to rest and relax, take things easy. Eat well, gets lots of water, sleep and avoid stress."
Try alternating small mental and physical tasks – a short walk, the washing up, a socially distanced meeting with a friend.
"If you are working on a computer," she says, "manage your screen time".
What's crucial to remember is that you can't exercise your way out of this, Donnelly says.
Nutritional therapist Clarissa Lenherr works for personalised health tech company Bioniq. She suggests going over your diet and prioritising three key foods: eggs, spinach and oats.
Lenherr explains: "Eggs are a rich source of good fats and protein, and the yolk is a source of vitamin D, calcium and vitamin A.
"Vitamin D plays an important role in energy production and immune system function, and low Vitamin D levels can lead to decreased energy levels, low mood, and potentially frequent bouts of illness."
Lenherr recommends spinach – especially for vegetarians or vegans – as it supplies vitamin K, magnesium and, most importantly, iron.
She explains: "Iron plays a key role in oxygen transport in our red blood cells and contributes to energy production in the body."
Oats are surely something we could all use more of: a source of complex carbohydrates, she explains, they provide us with a slow consistent release of energy.
It would be worth looking at overall stress too, as many of us who haven't had Covid-19 are feeling fairly washed out too.
"This has been an extremely stressful time," says Donnelly. "We have all felt physical and mental stress we haven't encountered before whether that's related to family, finances, or the news."
Forster is desperate to get back to normal. "It's been really tough,' she says. 'I can't wait for the day I wake up and don't feel 80 years old."