Inclusion Criteria:  Aged 18 to 45 years on the day of inclusion Participant signed informed consent Residing in Switzerland  Exclusion Criteria:  Participant is pregnant, lactating or of childbearing potential Participation in the 4 weeks preceding the first trial vaccination or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device or medical procedure. Receipt of any vaccine (including vaccine against COVID) in the 4 weeks preceding the first trial vaccination (excluding influenza vaccination which may be received 2 weeks prior to the first vaccination), or planned receipt of any vaccine in the 4 weeks following each trial vaccination. Positive SARS-CoV2 test in the 4 weeks preceding the first trial vaccination. Receipt of immunoglobins, blood or blood-derived products in the past 3 months. Known, or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy. Self-reported or documented seropositivity for human immunodeficiency virus (HIV), hepatitis B natural infection, (HBcAb positive serology) or hepatitis C. Known systemic hypersensitivity to any of the vaccine components (e.g gold,) or history of a life-threatening reaction to vaccines. Current alcohol abuse or drug addiction (reported or suspected) Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion. Thrombocytopenia or any coagulation disorder Identified as an Investigator or employee of the Investigator or study centre with direct involvement in the proposed study, or identified as an immediate family member (i.e parent, spouse, natural or adopted child) of the Investigator or employee with direct involvement in the proposed study (i.e in the employment of the Tropivac Clinic or DFRI unit at Unisante). Refusal to be informed in the event that relevant results concerning the participant's health are revealed.  The following events constitute contraindications to the administration of the investigational product on the day of planned vaccination: The participant must be followed until resolution of the event as with any medical event and may be considered for vaccination at a later date (maximum 14 days later) or withdrawn at the discretion of the Investigator. Delays due to these events do not constitute a protocol deviation.  Temperature of >37.5°C at the time of vaccination Acute disease at the time of vaccination (defined as the presence of a moderate or severe illness with or without fever according to investigator's judgment. All vaccines can be administered to persons with a minor illness such as diarrhoea, mild upper respiratory infection with or without low-grade febrile illness, i.e. axillary temperature of ≤ 37.5°C).