(1) The peptides of the vaccine, derived from the S proteins with the good immune activity of the current common PEDV and PDCoV strains, have a more promising protective effect for the host in either the case of the current epidemic PEDV or PDCoV infection alone or in the case of co-infection than the original peptide molecules for the prevention of PEDV or PDCoV alone. This evidence concerns the gene PROS1 and coinfection.