A Phase 1/2 Study to Determine Safety and Immunogenicity of Two COVID 19 Vaccines VB10.2129 (RBD Candidate) and VB10.2210 (T Cell Candidate) Previously Vaccinated in Healthy Adult Volunteers

Main inclusion criteria: * Give informed consent by signing the Informed Consent Form (ICF) SARS CoV 2 vaccination status for Part 1: 1. VB10.2129 (C1): have received 2 or 3 doses of an approved mRNA SARS CoV 2 vaccine, minimum 4.5 months (20 weeks) prior to Visit 1. 2. VB10.2210 (C2): have received 2 doses (primary vaccination) or 3 (primary and boost) doses of an approved mRNA SARS CoV 2 vaccine, minimum 8 weeks prior to Visit 1. SARS CoV 2 vaccination status for Part 2: VB10.2129 (C1) and VB10.2210 (C2) Vaccination status prior to Visit 1 will be decided based on data from Part 1. * Willing and able to comply with scheduled visits, treatment schedule, laboratory tests, lifestyle restrictions (eg, local law and regulations \[county specific lock down rules\] regarding COVID-19), and other requirements of the study. * Healthy, in the clinical judgement of the Investigator, based on medical history, physical examination, 12-lead electrocardiogram (ECG), vital signs (systolic/diastolic blood pressure, pulse rate, body temperature, respiratory rate), and clinical laboratory tests (blood chemistry, haematology, and urine chemistry) at Visit 0 (Screening). * Women of childbearing potential (WOCBP) must have a negative pregnancy test and must agree to practice a highly effective form * Agree not to be vaccinated with any other vaccine during the study until 28 days after receiving the last study vaccination * Negative rtPCR-test for SARS-CoV-2 Main exclusion criteria: * Have had any acute illness with or without fever, within 72 hours prior to the first vaccination * Symptoms of upper respiratory infection, fever, persistent cough, shortness of breath, runny nose and breathing difficulties * Breastfeeding or who plan to breastfeed during the study * Have a known allergy, hypersensitivity, or intolerance to aminoglycosides * Had any clinically significant or chronic medical condition or any major surgery within the past 5 years which * Have any surgery planned during the study * Had any chronic use of any systemic medications, including immunosuppressant's, oral corticosteroids or other immune-modifying drugs, within the 12 months prior to Screening * Received any vaccination within the 28 days prior to Screening * Received any prescription medicines (except hormonal contraception for WOCBP) within 14 days prior to Visit 0 (Screening) or over the counter medicines (except paracetamol and acetaminophen at a dose of (≤2 grams/day)) within 48 hours of Visit 0. * Have a known history or a positive test of HIV 1 or 2, Hep B, or Hep C * Have a positive rtPCR test for SARS-CoV-2 within 2 days of Screening * Documented history of previous infection with SARS-CoV-2 and/or who have the presence of serum Ab indicative of a previous SARS-CoV-2 infection * Have a history of hypersensitivity or have had a serious reaction to a previous vaccination * Have any abnormality or permanent body art (eg, tattoo) that, would obstruct the ability to observe local reactions at the injection site. * Have a condition known to put them at high risk for severe COVID-19, including those with any of the following risk factors: Hypertension, diabetes mellitus, chronic pulmonary disease, asthma, chronic liver disease, known stage 3 or worse chronic kidney disease * Anticipating the need for immunosuppressive treatment within the next 6 months. Other inclusion or exclusion criteria may apply.