* patients with active cancer and immunocopromised patients * known hypersensitivity to nivolumab or to any of their excipients. * pregnancy * patient with an autoimmune or inflammatory disease (including but not limited to: crohn's disease, rheumatoid arthritis, scleroderma, systemic lupus erythematosus, grave's disease). patients with thyroiditis or vitiligo only could be included. * patient with a history of thymoma * patient with a history of solid organ transplantation or a bone marrow transplantation * patients treated with immune checkpoint inhibitors 3 months prior to the study * patients who had a history of grade 3 or 4 immune-related adverse events with a previous treatment with immune-checkpoint inhibtors * patients requiring icu based on criteria of severity of covid pneumopathy * respiratory failure requiring mechanical ventilation or extracorporeal membrane oxygenation

* patients with active cancer and immunocopromised patients * known hypersensitivity to nivolumab or to any of their excipients. * pregnancy * patient with an autoimmune or inflammatory disease (including but not limited to: crohn's disease, rheumatoid arthritis, scleroderma, systemic lupus erythematosus, grave's disease). patients with thyroiditis or vitiligo only could be included. * patient with a history of thymoma * patient with a history of solid organ transplantation or a bone marrow transplantation * patients treated with immune checkpoint inhibitors 3 months prior to the study * patients who had a history of grade 3 or 4 immune-related adverse events with a previous treatment with immune-checkpoint inhibtors * patients requiring icu based on criteria of severity of covid pneumopathy * respiratory failure requiring mechanical ventilation or extracorporeal membrane oxygenation

- patients with active cancer and immunocopromised patients - known hypersensitivity to nivolumab or to any of their excipients. - pregnancy - patient with an autoimmune or inflammatory disease (including but not limited to: crohn's disease, rheumatoid arthritis, scleroderma, systemic lupus erythematosus, grave's disease). patients with thyroiditis or vitiligo only could be included. - patient with a history of thymoma - patient with a history of solid organ transplantation or a bone marrow transplantation - patients treated with immune checkpoint inhibitors 3 months prior to the study - patients who had a history of grade 3 or 4 immune-related adverse events with a previous treatment with immune-checkpoint inhibtors - patients requiring icu based on criteria of severity of covid pneumopathy - respiratory failure requiring mechanical ventilation or extracorporeal membrane oxygenation

- patients with active cancer and immunocopromised patients - known hypersensitivity to nivolumab or to any of their excipients. - pregnancy - patient with an autoimmune or inflammatory disease (including but not limited to: crohn's disease, rheumatoid arthritis, scleroderma, systemic lupus erythematosus, grave's disease). patients with thyroiditis or vitiligo only could be included. - patient with a history of thymoma - patient with a history of solid organ transplantation or a bone marrow transplantation - patients treated with immune checkpoint inhibitors 3 months prior to the study - patients who had a history of grade 3 or 4 immune-related adverse events with a previous treatment with immune-checkpoint inhibtors - patients requiring icu based on criteria of severity of covid pneumopathy - respiratory failure requiring mechanical ventilation or extracorporeal membrane oxygenation