<p>The invention relates to influenza virus vaccines, and in particular to a reassortant influenza virus which has at least its haemagglutinin gene derived from a non-pathogenic or low pathogenic influenza virus, and its other genes derived from a donor strain. In one embodiment the influenza virus is a 7:1 reassortant, in which only the haemagglutinin gene is derived from a non-pathogenic influenza virus. The virus is useful for production of vaccines against influenza, including influenza caused by highly pathogenic influenza virus strains.</p>
