INCLUSION CRITERIA :  General inclusion criteria for all patients of all groups  Be 18 years or older Get vaccinated against Covid-19 as part of the national vaccination campaign Accept the conditions of participation corresponding to each sub-population Commit to respecting the schedule of visits provided in the research protocol Plan to reside in France for at least 2.5 years from inclusion date Give their free, informed and written consent (at the latest on the day of inclusion and before any examination / samples) by signing the consent form Be a member of or beneficiary of a social security scheme (State Medical Aid is not a social security scheme).  General inclusion criteria for patients with a chronic condition of interest  • Present at least one pathology listed in the part listed above  Inclusion criteria specific to Solid Organ Transplantation  Not presenting intercurrent infections (cholangitis...) No prior anaphylaxis and cellular or humoral rejection within 3 months Having more than 3 months of remission after treatment with Thymoglobulin or Rituximab  Inclusion criteria for control subjects • Be free from the chronic conditions of interest listed in the context section or other chronic conditions/treatment that may affect the immune response  Inclusion criteria for control subjects free from chronic conditions of interest and with first injection with Astra-Zeneca vaccine AZD1222 and second injection with Pfizer ARNm vaccine BNT162b2  • Be vaccinated with a first injection with Astra-Zeneca vaccine AZD1222 and a second injection with Pfizer ARNm vaccine BNT162b2  NON INCLUSION CRITERIA :  General non inclusion Criteria for all participants of all groups  Be under protective supervision (guardian or curatorship) Being a pregnant or breastfeeding woman Present a contraindication to Covid-19 vaccination : Have a known or suspected allergy to any component of the vaccine, Have had at-risk contact with a confirmed Covid-19 person in the last 7 days, Have presented clinical signs suggestive of Covid-19 in the last 7 days, Have an acute febrile episode on inclusion / vaccination, Have received a vaccine in the last 15 days ... Have had a documented Covid-19 Infection (PCR or antigenic test) Refuse that their Social Security number is collected for accessing the National Health Data System (NSDS)/Data Health Hub national health databases For safety reasons, must agree to not enter in a vaccine clinical trial during the entire period of inclusion and follow-up of the research  Specific non inclusion criteria for PLWHIV  Being infected with HIV-2 Presenting another cause for immunosuppression (undergoing immunosuppressive treatment, biotherapy) Presenting a non controlled opportunistic infection  Specific non-inclusion for control subjects  Have one or more of the chronic conditions of interest listed above or affected by any other pathology or treatment that may affect the immune response (autoimmune/inflammatory pathology or immune deficiency not listed above, liver failure, immunosuppressive therapy (like oral corticosteroids at >= 10 mg/d Prednisone equivalent for more than 15 days) or radiotherapy within 6 months prior to inclusion or planned for the duration of the study) Life expectancy of less than 2 years