According to WHO, approximately 6% of the worldwide population who contract COVID-19—some 400 million people—go on to develop a long-lasting form of the disease. These figures demonstrate that the persistent form of the disease remains a problem and is a major public health challenge. In 2021, in the midst of the COVID-19 pandemic, University of Louvain (UCLouvain, Belgium) and its hospital, the Cliniques universitaires Saint-Luc, launched a large-scale study to determine whether it is possible to predict, during the acute phase of infection, the development of long-term symptoms.