Inclusion Criteria:  Age superior to 18 years old Patient undergoing maintenance treatment for Mantle Cell Lymphoma or Follicular Lymphoma treated with rituximab or obinutuzumab in complete remission or stable disease between injection #1 and injection #13 or 19 (end of second year or third year) Inform consent signed  Exclusion Criteria:  Documented history of SARS-Cov-2 infection less than 3 months old Progressive lymphoma Contraindication SARS-Cov-2 vaccination (allergy) Refusal of SARS-CoV-2 vaccination Patient who has been off rituximab or obinutuzumab therapy for more than 6 months Patient not covered by health system Pregnant or nursing woman