The "avian-like" H1N2 subtype, which has been established in the Danish pig population at least since 2003, is a reassortant between circulating swine "avian-like" H1N1 and H3N2. The Danish H1N2 has an "avian-like" H1 and differs from most other reported H1N2 viruses in Europe and North America/Asia, which have H1-genes of human or "classical-swine" origin, respectively. The variant seems, however, also to be circulating in countries like Sweden and Italy. The infection dynamics of the reassorted "avian-like" H1N2 is similar to the older "avian-like" H1N1 subtype.
Swine flu reassortment graphic courtesy of Russell Kightley Media