Abstract: The products of the invention are obtained by a method which consists of: oxidizing cytidine-diphosphocholine, fixing the dialdehyde obtained by the preceding oxidation of the ribose of the cytidine on NH.sub.2 groups of the amino compound in alkaline aqueous solution, stabilizing the coupling thus formed by reduction and recovering the macromolecular product thus obtained in the form of an aqueous solution. The latter can be freeze-dried to provide a powder suitable for preservation. The coupling occurs between the oxidized ribose groups of the cytidine-diphosphocholine and the lysine residues of the amino compounds. The products of the invention are suitable as vaccines against parasites belonging to the class of those including molecules bound to a phosphorylcholine residue, such as intestinal or respiratory parasites.