Researchers show how Covid-19 changes the size and stiffness of red and white blood cells Using real-time deformability cytometry, researchers at the Max-Planck-Zentrum für Physik und Medizin in Erlangen were able to show for the first time: Covid-19 significantly changes the size and stiffness of red and white blood cells - sometimes over months. These results may help to explain why some affected people continue to complain of symptoms long after an infection (long Covid). Shortness of breath, fatigue and headaches: some patients still struggle with the long-term effects of a severe infection by the SARS-CoV-2 coronavirus after six months or more. This post Covid-19 syndrome, also called long covid, is still not properly understood. What is clear is that -- during the course of the disease -- often blood circulation is impaired, dangerous vascular occlusions can occur and oxygen transport in is limited. These are all phenomena in which the blood cells and their physical properties play a key role.