The present invention relates to 2′-spirothietane nucleosides, and the phosphates and the prodrugs thereof, and the pharmaceutically acceptable salts and solvates thereof, and the use of such compounds as a medicament, in particular in the prevention and/or treatment of viral infections caused by viruses belonging to the Flaviviridae family and/or to the alphavirus genus. The present invention furthermore relates to pharmaceutical compositions or combination preparations of the compounds, and to the compositions or preparations for use as a medicament, more preferably for the prevention or treatment of viral infections caused by viruses belonging to the Flaviviridae family and/or to the alphavirus genus. The invention also relates to processes for the preparation of the compounds.