People with long Covid have evidence of continuing inflammation in their blood, which could help understanding of the condition and how it may be treated, a UK study suggests.

It found the presence of certain proteins increased the risk of specific symptoms, such as fatigue, in people sick enough to need hospital treatment.

It is unclear whether milder cases of Covid have the same effect on the body.

A test remains a long way off - but the findings may prompt future trials.

Long Covid - symptoms lasting at least 12 weeks after a Covid infection - is thought to have affected millions of people around the world.