Chronic fatigue, breathlessness, brain fog, anxiety and stress are just some of the ways long Covid can manifest.
ONS estimates around one in 10 people will experience the illness after testing positive for Covid-19.
One of them is 49-year-old Sally Carroll from Caterham.
Sally had no health problems and enjoyed an active lifestyle prior to being diagnosed, but for the last eight months has suffered debilitating effects of the illness.
In June last year, Sally developed a cough but recalls it being minor and without other symptoms related to Covid-19, such as a high temperature or a loss or change in sense of smell or taste.
Signing up to the SurreyLive newsletter means you'll receive our daily news email.
It couldn't be simpler and it takes seconds - simply press here, enter your email address and follow the instructions.
You can also enter your address at the top of this page in the box below the picture on most desktop and mobile platforms.
Changed your mind? There's an 'unsubscribe' button at the bottom of every newsletter we send out.
It was so slight, Sally said, she did not suspect it was coronavirus-related and when she got tested several weeks later the result was negative.
But over several months her condition progressively deteriorated.
By the end of October she was unable to walk three stairs or to the end of her road, which was flat, without losing her breath.
"Bending down to put the socks on I just felt like I couldn't breathe. I felt like I couldn't inflate my lungs, they would go so far and then there would be a pain," she said. Describing the sensation, Sally said: "It feels like somebody is sat on your chest."
She began to feel fatigued and suddenly simple tasks such as supermarket shopping were exhausting and took far longer than they should.
Her work was also affected. Sally, a fraud investigator, explained: "The breathing got worse and the coughing got worse. I interview quite a lot as part of my job, so I was having to stop doing that as I was just coughing and spluttering all the time over Skype.
"Physically, it stops you from wanting to go anywhere - you're either out of breath or the length of time things take get longer. It did affect everything really."
At the end of October Sally went to her GP and underwent blood tests and X-rays which didn't reveal any problems. She was put on a course of antibiotics, but the symptoms did not subside.
It was then that Sally was diagnosed with long Covid, with the doctor concluding she caught the virus earlier in the year.
The doctor referred her to First Community, a community healthcare provider, which has launched a special long Covid rehabilitation service.
An assessment of Sally was carried out and she was placed onto a six-week course. The long Covid rehab team includes stroke, respiratory and physiotherapy specialists.
She was provided with breathing exercises to do at home and has had to re-train her lungs. Now in her final week of the rehab course, Sally says the difference is "amazing".
"Before, I would walk up a slight incline and I would have to stop, or I'd be puffing at the top and my heart would be racing. But because I have been taught how to breathe properly it has really improved," she said.
However, Sally still gets out of breath quicker than she would pre-Covid, and admitted "I still can't do things I could before".
She has also noticed her attention span has reduced and has to take more frequent breaks from work to re-focus. The tiredness has also not gone away completely.
Not knowing why long Covid has affected her, as it has so many others, has been anxiety-inducing.
Sally said: "I have good days and bad days. There are still days where it is a struggle to get up the hill. But the difference is huge [compared to before long Covid therapy].
"I do wonder why it affected me in this way. Before I could quite easily go for walks and not be out of breath, so that has been quite hard to cope with. The fact that it is still there now is a bit worrying because I think, what else is it doing if it has been lingering around for so long?"
Sally has not been given any indication of how long her symptoms will persist. Her six-week course is drawing to a close and at the end of it she will be assessed. If needed, her therapy may be extended.
Sally said: "I now feel I can inflate my lungs 85 per cent. There is still a tightness there, but compared to where it was it is massively different. If it keeps improving then brilliant, if it stays like this it is something I can live with, but is not as great as it should be."
Demand increasing for long Covid rehab
Janet Clark, First Community service manager for Long Term Condition Support Services, has reported a "steadily increasing" demand for long Covid rehabilitation.
She said: "We are finding that there is no one type of person being affected by one typical type of problem when it comes to long Covid.
"We are now starting to see a lot of younger patients, those that are 29, 30, 34 years of age, that have had the virus and not necessarily gone to their GP at the onset of their problems, but months later are still experiencing difficulty."
Knowledge and learning about the long-term effects of Covid-19 are continuing to develop as it remains a relatively new phenomenon.
Janet said she anticipates there will be an ongoing need for support. Adding: "I'd encourage anyone struggling with their recovery after having Covid-19 to speak to their GP, who can assess, advise and refer them to the long Covid pathway if appropriate.
"You may have a wait due to the demand on the service and community services as a whole at present, but we will see you, and will do all we can to support you in your recovery."