For most people, COVID-19 is a fairly mild and short-lived disease. But some find themselves wrestling for months with debilitating symptoms including extreme fatigue, persistent joint pain, muscle aches and shortness of breath.
One of them is Paul Garner, who happens to be an epidemiologist specialised in infectious diseases at the Liverpool School of Tropical Medicine. He documented his own struggle with "long COVID" in the British medical journal the BMJ earlier this year, describing it as "a roller coaster of ill-health, extreme emotions, and utter exhaustion".
Before he first developed symptoms of COVID-19 in March, Garner says he used to run a lot and would do military fitness exercises. So he expected to develop only a mild form of the disease.
"But it absolutely floored me,” Garner, who has now been ill for over six months, told Euronews.
"It’s a little bit like a grenade has gone off in your hands, and there’s damage to your tissues all over the place, and you’re busy trying to recover and work out what it is," he explained.
"It’s the immunological response, almost the body over-responding to the condition, and it’s trying to protect you. It tries to stop you doing too much, to allow the body time to recover."
"So the treatment for a lot of us is really being a bit careful, eating well, resting and doing some gentle exercise to keep ourselves mobile."
Watch more of the interview in the video player above.