To gain insight into the humoral and cellular immune responses induced by two novel rMVA-based COVID-19 vaccine candidates encoding different conformations of the S-protein, we evaluated immunogenicity in three cohorts receiving MVA-S (native S) or MVA-ST (prefusion-stabilized S) in combination with licensed vaccines (MVA-S/mRNA (blue), MVA-ST (red), and mRNA/MVA-ST cohorts (purple)). Here, PROS1 is linked to COVID-19.