Changes to white and red blood cells caused by the coronavirus may explain why so many patients suffer from long Covid, researchers have found.
The virus alters the size and stiffness of these blood cells, making it harder to get oxygen and other vital nutrients around the body.
German researchers found that these blood cell changes can last for months, which may explain why many patients become ‘long haulers’.
They believe the physical alterations are leading to the most common symptoms reported in long Covid – breathing difficulties, tiredness and headaches.
But it may also be part of the reason why so many very sick Covid patients develop blood clots or suffer organ damage.
Scientists from the Max Planck Center for Physics and Medicine in Germany, who made the finding, analysed blood samples of 31 current and former Covid patients and compared them to healthy volunteers.
Long Covid is an umbrella term encompassing symptoms that persist for more than a month and is poorly understood.
Most long Covid sufferers only have symptoms for a month after beating the initial infection, but millions still suffer six months later and hundreds of thousands have them for a year.
Oxford University scientists estimate that more than 2million people in England have suffered from the condition during the pandemic.
Fatigue was the most common symptom, affecting an estimated 535,000 people, followed by shortness of breath striking 397,000 and muscle ache hitting 309,000, according to the Office for National Statistics
The researchers found that blood cells were different sizes and shapes in people who were healthy (left), previously had the virus (middle) and had currently had the virus and were hospitalised (right). The graphs show how deformation increased slightly for people who had the virus, while those currently infected had cells that were much more deformed
The graph on the left estimates what blood cells look like in health (grey), recovered (green) and currently infected (yellow) patients
WHAT ARE THE LONG-TERM SYMPTOMS OF COVID-19?
Most coronavirus patients will recover within a fortnight, suffering a fever, cough and losing their sense of smell or taste for several days.
However, evidence is beginning to show that the tell-tale symptoms of 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
For those with more severe disease, Italian researchers who tracked 143 people who had been hospitalised with the disease found almost 90 per cent still had symptoms including fatigue two months after first falling unwell.
The most common complaints were fatigue, a shortness of breath and joint pain – all of which were reported during their battle with the illness.
The researchers found volunteers who had Covid suffered poorer blood circulation, limited oxygen transport and blood clots.
‘These are all phenomena in which the blood cells and their physical properties play a key role,’ they said in their report, which was published last month in Biophysical Journal.
The scientists examined over four million blood cells from 17 patients acutely ill with Covid aged between 41 and 87, from 14 people aged 27 to 76 who recovered and from 24 healthy people aged 26 to 81 as a comparison group.
They measured the shape of red and white blood cells using a microscopic camera and analysed the data on a computer.
Red and white blood cells – vital for carrying oxygen and nutrients around the body were found to be drastically different sizes and shapes in Covid patients.
The researchers believe this can make blood clumpy and therefore harder to get oxygen around the body.
White blood cells are part of the immune system and help your body fight infections, while red blood cells carry oxygen from your lungs to all the cells in your body.
Additionally, they found that the size and form of white blood cells in patients with the virus were very different from those of healthy people.
This indicates damage to these cells and could explain the increased risk in Covid patients of blood clots and pulmonary embolisms, which is when a blood vessel in the lung is blocked by a blood clot.
The scientists believe that the persisting changes of blood cells could contribute to the long-term impairment of circulation and oxygen delivery linked with the virus.
Before the study, physical changes of blood cells were not considered as playing a role in Covid-19 related vascular occlusion and organ damage, the scientists said.
Scientists had not yet figured out what was to blame, with the condition not being fully understood.
Last month, the Government provided scientists with £50million to study the condition.
The NHS has opened 80 long-Covid assessment clinics across England to improve diagnosis and patient care.
A separate study by the Office for National Statistics found that nearly one million people in the UK were suffering from long-Covid in May.
An estimated 962,000 people were experiencing long-Covid in the four weeks to June 6.
The number of people struggling with persistent symptoms that had gone on since last summer jumped from 376,000 last month to 385,00, according to the ONS.
Their data showed that around two-thirds of those with long Covid said it restricted their ability to carry out day-to-day activities.
The ONS’ results follow on from findings from Imperial College London, which were published last week, that a third of the 500,000 patients they studied reported at least one lingering Covid symptom 12 weeks after the initial illness.
The most commonly reported symptoms included tiredness, shortness of breath, muscle aches and difficulty breathing.
Broadening their results to the wider population, the researchers estimated that two million people – or one in 30 – will have suffered from long Covid months after clearing the disease.