The core experience of long Covid revolves around the unholy trinity of fatigue, brain fog and muscle pain. But there is a long list of rarer symptoms covering almost every bodily function ranging from digestive problems to night sweats and depression to hair loss.
The Office for National Statistics says one in 40 people have symptoms that last at least three months after an infection. Around 1.5 million people in the UK say they have long Covid symptoms with growing numbers (685,000) saying their long Covid has lasted longer than a year.
[U]nderstanding the range of possible causes of long Covid is giving new ideas for therapies.
High levels of inflammation mean there is a good argument that antihistamines may become very important, says Prof Brightling, as the drugs could calm the immune response down in the same way they do in allergies.
Blood-thinning drugs that make it harder for clots to form are being investigated and even drugs that boost mitochondria function are being trialled.
Meanwhile, if long Covid is caused by a persistent infection it raises the prospect of antivirals, vaccines or lab-made antibodies being useful.