Long Covid could be caused by an overload of tiny clots ‘trapped’ inside people’s blood weeks after they clear the initial infection, scientists say.
The small study found patients who are ‘long haulers’ have a large amount of inflammatory molecules trapped in their bloodstream.
These blockages have the potential to disrupt the body’s ability to distribute oxygen and vital nutrients, they said.
It could explain long Covid’s most common symptoms, such as fatigue, headaches and breathing difficulties.
The South African researcher who made the discovery said the micro clots may be the cause of long Covid or one of several contributing factors.
A scientist has found long Covid patients have micro clots in their blood months after the initial infection. On the left is an image of healthy blood plasma (blood plasma is the largest type of fluid which forms blood, accounting for 55 per cent of the total) and on the right is an image of one of the micro clots found in the blood. The material contained in both samples were highlighted using florescent materials for analysis.
The South African researcher who made the discovery said the micro clots may be the cause of long Covid or one of several contributing factors (file)
The new discovery came from Professor Resia Pretorius from the department of physiological science at Stellenbosch University.
Professor Pretorius compared blood collected from 11 people with long Covid and 13 healthy individuals.
What is long Covid?
Most coronavirus patients will recover within a fortnight, suffering a fever, cough and losing their sense of smell or taste for several days.
However, the virus can persist for weeks on end in ‘long haulers’ — the term for patients plagued by lasting complications.
Data from the Covid Symptom Study app, by King’s College London and health company Zoe, suggests one in ten people may still have symptoms after three weeks, and some may suffer for months.
Long term symptoms include:
- Chronic tiredness
- Raised heart rate
- Loss of taste/smell
- Kidney disease
- Mobility issues
- Muscle pains
‘We found high levels of various inflammatory molecules trapped in micro clots present in the blood of individuals with long Covid,’ she said.
‘Some of the trapped molecules contain clotting proteins such as fibrinogen, as well as alpha(2)-antiplasmin.’
Fibrinogen is a protein found in blood and helps the body make clots to stop bleeding.
Alpha(2)-antiplasmin is a molecule that helps prevent blood clots from breaking down.
Under normal conditions, the body maintains a balance of clotting and anti clotting material to help the body reduce blood loss after injury.
This also prevent clots from growing too large and restricting oxygen flow.
Professor Pretorius said high amounts of alpha(2)-antiplasmin being stuck in the blood means the body’s ability to break down clots is severely reduced.
What causes long Covid has baffled scientists since the phenomenon was observed.
But other recent studies have also highlighted that the body’s clotting system could be involved.
An study from the Royal College of Surgeons in Ireland showed clotting markers were elevated among the people with long Covid months after their initial infection.
And Covid itself has been linked to clotting disorders during the initial infection that in some cases can be fatal.
Data from the Office of National Statistics in August suggested almost 400,000 people in the UK have been suffering from long Covid for more than a year.
Long Covid is an umbrella term encompassing symptoms that persist for more than a month and is poorly understood.
Professor Pretorius said more research is needed to confirm her findings, with a larger sample size.
She also recommended more research into what type of treatment to support long Covid patients’ clotting system is needed.
Her findings have been published in the medical journal Cardiovascular Diabetology.