inclusion criteria: - healthy adults ≥18 and <56 years (cohort a) and ≥56 years and <70 years (cohort b) as determined at the day of signing informed consent - sars-cov-2 rt-pcr (nasal swab) negative at day 1 pre-dose - women of childbearing potential (wocbp) or male subjects with partners who are wocbp must agree to practice contraception during their study participation from the signing of informed consent for at least 3 months after the final mv-014-212 administration. - written informed consent

inclusion criteria: - healthy adults ≥18 and <56 years (cohort a) and ≥56 years and <70 years (cohort b) as determined at the day of signing informed consent - sars-cov-2 rt-pcr (nasal swab) negative at day 1 pre-dose - women of childbearing potential (wocbp) or male subjects with partners who are wocbp must agree to practice contraception during their study participation from the signing of informed consent for at least 3 months after the final mv-014-212 administration. - written informed consent

inclusion criteria: - healthy adults ≥18 and <56 years (cohort a) and ≥56 years and <70 years (cohort b) as determined at the day of signing informed consent - sars-cov-2 seronegative (both igm and igg) at screening - sars-cov-2 rt-pcr (nasal swab) negative at day 1 pre-dose - women of childbearing potential (wocbp) or male subjects with partners who are wocbp must agree to practice contraception during their study participation from the signing of informed consent for at least 3 months after the final mv-014-212 administration. - written informed consent

inclusion criteria: - healthy adults ≥18 and <56 years (cohort a) and ≥56 years and <70 years (cohort b) as determined at the day of signing informed consent - sars-cov-2 seronegative (both igm and igg) at screening - sars-cov-2 rt-pcr (nasal swab) negative at day 1 pre-dose - women of childbearing potential (wocbp) or male subjects with partners who are wocbp must agree to practice contraception during their study participation from the signing of informed consent for at least 3 months after the final mv-014-212 administration. - written informed consent