Immunogenicity and Reactogenicity of the Beta-variant Recombinant Protein Booster Vaccine (VidPrevtyn Beta, Sanofi) Compared to a Bivalent mRNA Vaccine (Comirnaty Original/Omicron BA.4-5, BioNTech-Pfizer) in Adults Previously Vaccinated With at Least 3 Doses of COVID-19 mRNA Vaccine (CoviBOOST 2)

Inclusion Criteria: Male or female aged 18 years and over Adult in a healthy condition or with a stable health status, determined by medical history, targeted physical examination and clinical judgement of the investigator to be in stable state of health. Participants with pre-existing stable chronic medical conditions defined as condition not requiring significant change in therapy or hospitalization for worsening disease within 4 weeks from enrollment can be included at the discretion of the investigator. For women of childbearing age: a negative highly sensitive pregnancy urinary test during the inclusion visit Confirmed receipt of at least three doses of COVID-19 mRNA vaccine the last dose at least 6 months prior to study vaccine Understands and agrees to comply with the study procedures Written informed consent signed by both the participant and the investigator Subject affiliated to the French Social Security System. Exclusion Criteria: Acute febrile infection (body temperature ≥ 38.0°C) within the previous 72 hours and/or presenting symptoms suggestive of COVID-19 within the previous 28 days Confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection < 3 months prior to the study vaccine dose. Immunosuppressive therapy such as corticosteroids > 10 mg prednisone equivalent/day (excluding topical preparations and inhalers) within 3 months prior to inclusion or within 6 months for chemotherapies. Treatment with immunoglobulins or other blood derivatives within 3 months prior to inclusion or scheduled administration of immunoglobulins or blood derivatives before the end of the study. Any medical condition, such as cancer, that might impair the immune response. Use of experimental immunoglobulins, experimental monoclonal antibodies or convalescent plasma is not permitted during the study. Pregnancy or breastfeeding currently ongoing History of severe adverse events following vaccine administration including anaphylactic reaction and associated symptoms such as rash, breathing problems, angioedema, and abdominal pain, or a history of allergic reaction that could be triggered by a component of the SARS-COV-2 vaccine at the time of the first vaccine injection: Any bleeding disorder considered as a contraindication to an intramuscular injection, Participation in other interventional research involving humans within 4 weeks prior to the inclusion visit, or participation in any other vaccine trial excepted for those with mid or long term follow up when vaccination was made at least 4 weeks before the injection in the study. In this case no delay is required after the end of the study participation". Subject under legal protection (e.g. guardianship)