Main inclusion criteria:  Give informed consent by signing the Informed Consent Form (ICF)  SARS CoV 2 vaccination status for Part 1:  VB10.2129 (C1): have received 2 doses of an approved mRNA SARS CoV 2 vaccine, minimum 6 months (26 weeks) prior to Visit 1. 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.