An attenuated swine influenza strain capable of providing a safe and effective immune response in a porcine animal against a virulent H3N2 swine influenza or diseases caused by H3N2 swine influenza. The attenuated strain encodes an HA protein comprising (i) four additional glycosylation sites, relative to its corresponding virulent parental strain and (ii) having at least 90% identity to a sequence as set forth in SEQ ID NO: 24, provided that the following locations have the following amino acids: 71N, 90N, 173T, 287T and wherein amino acid 294 is not 294T. The virulent parental strain is an H1N1 swine influenza strain encoding an HA protein having the sequence as set forth in SEQ ID NO:18.
