The present invention concerns a composition comprising micro particles of polyinosinic-polycytidylic acid (Poly (I:C)) and a carrier polymer selected from starch, alginate, blanose or DPPC (dipalmitoylphosphatidylcholine) for use in preventing and/or treating viral infections of the upper respiratory tract or the common cold and a device, preferably a nasal delivery system, comprising said composition for use by a patient in need to prevent and/or treat infections or the common cold.