Provided is a polypeptide having no more than 100 amino acids, which polypeptide comprises one or more sequences having at least 60% homology with any of SEQ ID 1-6, or comprises two or more epitopes having 7 amino acids or more, each epitope having at least 60% homology with a sub-sequence of any of SEQ ID 1-6 that has the same length as the epitope:SEQ LID 1 DLEALMEWLKTRPILSPLTKGILGFVFTLTVPSEQ ID 2 LLYCLMVMYLNPGNYSMQVKLGTLCALCEKQASHSSEQ ID 3 DLIFLARSALILRGSVAHKSCSEQ ID 4 PGIADIEDLTLLARSMVVVRPSEQ ID 5 LLIDGTASLSPGMMMGMFNMLSTVLGVSILNLGQSEQ ID 6 IIGILHLILWILDRLFFKCIYRLFwherein, the polypeptide is immunogenic in a vertebrate expressing a major histocompatibility complex (MHC) allele, and wherein the polypeptide is not a complete influenza virus protein.
