The invention provides a polypeptide comprising an influenza hemagglutinin HA1 domain that comprises an HA1 N-terminal stem segment covalently linked to a linker of 1 to 50 heterologous residues that is in turn covalently linked to an HA1 C-terminal stem segment said HA1 domain being in tertiary association with an influenza hemagglutinin HA2 domain. Further provided are a nucleic acid encoding the polypeptide of the invention, a cell expressing said nucleic acid, a virus comprising or expressing the polypeptide of the invention, an immunogenic composition comprising any of the above subject matter as well as its use in a method of immunizing a subject against an influenza virus disease or an influenza virus infection.
