Possible causes of long COVID discovered | Knowledge & Environment | DW

Many former COVID-19 patients suffer from severe long-term consequences of long-COVID after the infection. The main symptoms are tiredness, exhaustion, headaches and shortness of breath. The symptoms can last for weeks, in some cases even for months. Even those who seem to have recovered are by no means really healthy.

COVID-19 often affects blood circulation. Thrombosis occurs, i.e. vascular blockages. In addition, the transport of oxygen in the blood may not work one hundred percent. Blood cells apparently have a major influence on long COVID.

Researchers from the Max Planck Center in Erlangen have put forward a new hypothesis in a study. Accordingly, the blood cells of COVID-19 patients have changed. This affects both the stiffness and the size of red and white blood cells. Blood cells and their physical properties therefore play a key role. The results of the study were published in the “Biophysical Journal”.

Shortness of breath is a symptom of post-Covid

Corona infected people have changed blood cells

In order to come to their result, the team from Erlangen had examined blood cells from people suffering from COVID, from those who have recovered and from healthy people. 17 people were acutely ill with COVID-19, 14 recovered and another 24 in the comparison group were healthy. A total of 400 million blood cells were examined.

“We were able to measure significant and long-lasting changes in the cells – both during and after an acute infection,” explained Jochen Guck in a press release from the Max Planck Institute in Erlangen, of which he is the managing director.

Icon picture thrombosis blood clot

Thrombosis is one of the long-term effects of COVID-19

A highly complex process

The researchers had developed the method with which the study was carried out themselves. It is called “real-time deformability cytometry” (RT-DC). In this method, blood cells are sent through a narrow channel. The white blood cells, the leukocytes, and the red blood cells, the erythrocytes, are stretched.

A high-speed camera photographs every single blood cell through a special microscope. Appropriate software then analyzes the size and degree of the respective deformation. The software can determine the condition of up to 1000 blood cells per second.

Pandemic early warning system?

In the case of the sick, the size and deformability fluctuated much more than in the healthy people tested. This indicates that the cells in the sick are damaged. In healthy people, the blood cells are elastic and fit through even the finest of veins.

DW fit & healthy - white blood cells

White and red blood cells change in COVID-19

Red blood cells (erythrocytes) have the shape of biconcave discs. Because they lack the cell nucleus, they can become deformed and also pass through blood capillaries whose diameter is only half the size of their own. In this way, they penetrate the most remote corners of the body and supply it with nutrients and oxygen.

The white blood cells (leukocytes) are also relatively small and, thanks to their many appendages on the cell surface, are easy to move. They play a central role in the immune system.

The blood cells of Long-COVID patients, on the other hand, are spherical and can clog the veins, which can lead to thrombosis and embolism.

The researchers hope to be able to use the new analysis method for faster, more reliable diagnosis in the future. In the best case scenario, an early warning system could have been discovered for future pandemics, which can then be traced back to as yet unknown viruses.

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