Safety and Immunogenicity of the Candidate Vaccine MVA-SARS-2-S and a Booster Vaccination With a Licensed Vaccine Against COVID-19

The vaccine contains a Modified Vaccinia Virus Ankara (MVA) vector expressing the SARS-CoV-2 spike protein (S). A total of 30 participants will receive the following vaccine regime: 15 participants will receive 10\^7 infectious units (IU) of MVA-SARS-2-S on days 0 and 28. 15 participants will receive 10\^8 IU of MVA-SARS-2-S on days 0 and 28. Safety and immunogenicity data will be collected throughout the study, which concludes at day 168. A subgroup will receive a heterologous booster vaccination with a licensed COVID-19 vaccine. Vaccinees will receive two doses of the Comirnaty vaccine (21 days interval).