Inclusion Criteria for Active RA Patients:  Patients with rheumatoid arthritis (RA) meeting the 2010 ACR/EULAR diagnostic criteria Patients in inflammatory flare of RA (DAS28 > 3.2) Patients who have been off biological disease-modifying antirheumatic drugs (bDMARDs) or targeted synthetic antirheumatic drugs (tsDMARDs) for RA for at least 2 weeks (except for rituximab, where a delay of at least 12 months is required) Conventional synthetic DMARDs (Methotrexate, Hydroxychloroquine, Leflunomide, Sulfasalazine) are allowed Beneficiary of a social security system Informed consent  Inclusion Criteria for Healthy Controls:  Absence of chronic diseases and current infection Beneficiary of a social security system Informed consent  Inclusion Criteria for COVID-19+ Patients:  Patients with ongoing SARS-Cov-2 infection (PCR+) Patients hospitalized at D7-D14 of symptoms onset Patients with two or more SARS-Cov-2 symptoms (including fever, cough, dyspnea, sore throat, chest pain, anosmia, diarrhea) Membership in or beneficiary of a social security scheme Collection of free and informed consent  Exclusion Criteria for All Groups:  Subjects under 18 years of age HIV positive patients Diabetic patients Morbidly obese patients (BMI > 40kg/m2) Use of senolytic drugs in the week prior to inclusion (azithromycin, metformin, cyclosporine, JAK inhibitors) Use of steroids in doses greater than 10 mg/day in the week prior to inclusion Subjects unable to give consent Pregnant, breastfeeding, or non-menopausal women not taking effective contraception Vulnerable subjects protected by law Subjects under guardianship or curatorship