An Experimental Medicine Multicenter Trial to Evaluate the Safety and Immunogenicity of Experimental Versus Authorized SARS-CoV-2 Vaccine Candidates as a Booster Dose in Healthy Participants Previously Vaccinated With Authorized mRNA SARS-CoV-2 Vaccines.

Exclusion criteria

• . Acute febrile infection (body temperature ≥ 38.0°C) within the previous 72 hours and/or presenting symptoms suggestive of COVID-19 or SARS-CoV-2 infection within the previous 28 days or having been in contact with an infected individual for the last 14 days before the inclusion visit
• . Any medical condition that could impair the immune response: clinically significant medical condition, physical examination findings, clinically significant abnormal laboratory results, or past medical history with clinically significant implications for current health. A clinically significant condition or process includes but is not limited to:
• . Pregnancy or breastfeeding that is currently ongoing, or positive pregnancy test at screening visit and the day of the vaccination
• . Immunodeficiency
• . Asthma: a condition that requires active medical intervention or monitoring to avert grave danger to asthma other than mild, well-controlled asthma. (Symptoms of asthma severity as defined in the most recent National Asthma Education and Prevention Program (NAEPP) Expert Panel report). Exclude a participant who:
• . Diabetes type 1 or type 2, including cases controlled with diet alone. (Not excluded: history of isolated gestational diabetes).
• . Thyroidectomy, or thyroid disease requiring medication during the last 12 months
• . Hypertension: