The invention provides methods of preventing and/or treating infection by a respiratory virus such as respiratory syncytial virus (RSV), particularly reducing infection and/or one or more symptoms of respiratory virus infection. A polynucleotide comprising an immunostimulatory sequence (an “ISS”) is administered to an individual which is at risk of being exposed to a respiratory virus, has been exposed to a respiratory virus or is infected with a respiratory virus. The ISS is administered without any antigens of the respiratory virus. Administration of the ISS results in reduced incidence and/or severity of one or more symptoms of respiratory virus infection.
