Inclusion Criteria:  Subject provides written informed consent Participant is ≥ 18 and ≤ 65 years of age on the day of signing the ICF Individuals that are eligible for vaccination according to the Austrian vaccination plan. Participants that have been vaccinated with either ChAdOx1-S prime within the last 12 weeks or BNT162b2 prime within the last 3 - 6 weeks Subject understands and agrees to comply with study procedures Subject must be willing to be contacted by telephone or willing to complete an eDiary during study participation  Female participants of childbearing potential may be enrolled in the study if the participant fulfills all the following criteria:  has a negative urine pregnancy test at screening has agreed to practice adequate contraception from providing consent until 3 months after administration of study vaccine is not currently breastfeeding Adequate female contraception is defined as consistent and correct use of an approved contraceptive method, for example: Barrier method (condoms, diaphragm, cervical cap) used in conjunction with spermicide Prescription hormonal contraceptive taken administered via oral (pill), transdermal (patch), subdermal or IM route Intrauterine device Sterilization of a female participant's monogamous male partner prior to study inclusion Cave: periodical abstinence (eg calendar, ovulation, symptothermal,...) and withdrawal are not acceptable methods of contraception. Female participants of non-childbearing potential may be enrolled in the study. Non-childbearing potential is defined as: surgically sterile (history of bilateral dubal ligation, bilateral oophorectomy, hysterectomy) or postmenopausal (amenorrhea for 12 consecutive months prior to Screening without an alternative medical cause). Participants agrees to not donate bone marrow, blood and blood products from the study vaccine administration until 3 months after receiving the study vaccine  Exclusion Criteria:  Participant has already received full vaccination against SARS- CoV-2 2. Prior administration of an investigational coronavirus (SARS- CoV, MERS-CoV) vaccine or current/planned simultaneous participation in another interventional study to either prevent or treat COVID-19 3. Participant has received/plans to receive a non-study vaccine within 14 days prior to or after any dose of IP 4. Participant has a contraindication to IM injections and blood draws (eg, bleeding disorders) 5. Participants has a known or suspected allergy or history of anaphylaxis, urticaria or other significant adverse reactions to vaccines or their excipients (including specifically the excipients of the study vaccine; refer to the IB) 6. Subjects with previous positive PCR-test result for SARS-CoV-2 or positive anti-SARS-CoV-2 N protein antibody test 7. History of leukemia, lymphoma, or underlying bone marrow disorder (eg, myelodysplasia, myeloma, myeloproliferative disorder) or history of bone marrow transplant. 8. Malignancy that required treatment with chemotherapy, immunotherapy, radiation therapy, or other antineoplastic target therapies within 24 months prior to study enrollment. 9. Has participated in an interventional clinical study within 30 days prior to study inclusion