Evaluation of Safety and Immunogenicity of a SARS-CoV-2(Severe Acute Respiratory Syndrome Coronavirus 2) Booster Vaccine (LEM-mR203)

Inclusion Criteria: * Healthy volunteer aged 19 years or older but less than 55 years at the time of screening. * Individuals falling into one of the following categories: * Those who have completed their primary vaccination with a domestically approved COVID-19 vaccine and have elapsed more than 90 days but less than 48 weeks since the completion of the primary vaccination. * Individuals who have completed their primary vaccination and received 1 or more additional doses; these individuals must have elapsed more than 4 months but less than 48 weeks since their last vaccination * Individuals who do not exhibit clinically significant respiratory symptoms (e.g., cough, sore throat) and do not have clinically significant active lesions on chest X-ray. * Individuals who agree to use medically accepted contraceptive methods during the entire study period before clinical trials * Individuals who agree not to donate blood or receive blood transfusions (including whole blood, plasma components, platelet components, and platelet plasma components) during the study period before clinical trials. * Individuals who can participate in all study visit schedules and comply with all study procedures. * Individuals who, after receiving detailed explanations about the clinical trial and fully comprehending it, voluntarily decide to participate, and provide written consent before the screening procedure. Exclusion Criteria: * Within 72 hours before administration of the investigational …