The present invention relates to synthetic fucosylated oligosaccharide for use in the treatment or prophylaxis of an infection with a Norwalk-like Virus or Rotavirus of a mammal, wherein the synthetic fucosylated oligosaccharide comprises a non-reducing end and an reducing end, wherein the reducing end comprises a first carbohydrate unit consisting of a galactose (Gal) linked via a ²1-4 glycosidic bond to a glucose (Glc), and wherein the non-reducing end comprises a second carbohydrate unit linked via a ²1-3 glycosidic bond to the first carbohydrate unit of the reducing end, and wherein the second carbohydrate unit comprises a) at least one or more of a fucose (Fucose) and a Galactose (Gal), and b) at least one or more of a N-acetylglucosamine (GlcNAc) or a N-acetylgalactosamine (GalNAc).
