PROS1 and respiratory tract infectious disorder: In our previous study (15), we determined that one or two IM injections of 2 × 107 PFU of a recombinant MVA (rMVA-Stri) expressing a SARS-CoV-2 S protein that had been triply modified by stabilization of the prefusion structure, inactivation of the furin cleavage site, and deletion of the endoplasmic retention signal, induced S-binding and neutralizing antibodies and protected transgenic K18-hACE2 mice from lethal respiratory infection with the Wuhan strain of SARS-CoV-2 (15).