COVID-19 infection manifests in its severe form as acute alveolo-interstitial and vascular pneumonitis. However, long-term outcome remains unknown. A progression to fibrosing pneumonia could affect 10 to 30% of survivors of severe forms, making it a public health problem through secondary disability. The project concerns the analysis of CT images of patients followed at the Avicenne APHP hospital (Bobigny) in collaboration with two expert image treatment/modelling teams for an evaluation of vascular remodelling and mechanical simulation of the regional lung compliance. These parameters obtained at 2-4 months of COVID-19 infection will be correlated with clinical, CT, and functional data at 6 months and 1 year follow-up. This project should make it possible to understand the COVID-19 infection manifests as an acute alveolo-interstitial and vascular pneumonitis in its severe form. However, long-term outcome remains unknown. It has been hypothesized that a progression to fibrosing pneumonia could affect 10 to 30% of survivors of severe forms, making it a public health problem through secondary disability. But there is no parameter which could currently allow to predict such an outcome. The SILICOVILUNG project is based on the CT images analysis of patients followed at the Avicenne APHP hospital (Bobigny, France) after severe COVID pneumonitis in collaboration with two expert image treatment/modelling teams \[ Artemis Telecom Sud-Paris (Evry, France) and LMS INRIA Ecole Polytechnique (Palaiseau, France)\] for an evaluation of vascular remodeling and mechanical simulation of the regional lung compliance using a poromechanical model. These parameters obtained at 2-4 months of COVID-19 infection will be correlated with clinical, CT, and functional data at 6 months and 1-year follow-up. This project should make it possible to understand the mechanisms of regional physiology in the evolution of COVID-19 pneumonias in their severe forms and to anticipate the development or not of sequelae, particularly fibrosing.