Study of a Recombinant Spike COVID-19 Vaccine With Matrix-M in Older Adults and People at Increased Risk of Severe COVID-19

Inclusion Criteria: To be included in this study, each individual must satisfy all the following criteria: * Participants ≥ 65 years of age, or participants 12 through 64 years of age who have at least 1 underlying condition that puts them at increased risk for severe outcomes from COVID-19 at the time of study vaccination. * Previously vaccinated with a COVID-19 vaccine, with the last dose administered ≥ 90 days prior to study vaccination. * Participants must not be pregnant or breastfeeding. Participants of childbearing potential must have a negative highly sensitive pregnancy test at enrollment and must agree to use an effective method of contraception or remain abstinent from ≥ 4 weeks before study vaccination through ≥ 4 weeks after vaccination. Exclusion Criteria: Participants are not eligible if any of the following criteria are met: * Known or suspected congenital or acquired immunodeficiency; receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the past 6 months; or long-term use of systemic corticosteroids. * History of virologically confirmed SARS-CoV-2 infection within 90 days before study vaccination. * Known systemic hypersensitivity to any component of the study intervention or a history of a life-threatening reaction to the study intervention or to a product containing the same substances. * Prior history of myocarditis, pericarditis, or myopericarditis. * Receipt of any vaccine within 28 days before study vaccination, except for influenza vaccine, which may be administered at least 14 days before study vaccination. * Receipt of an investigational or marketed COVID-19 vaccine within 90 days before study vaccination. The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.