Who knows how it got to S. Korea, but we are doing it to ourselves right now in America-its called the 'avian flu vaccine'.
Some overpaid AMA medical scientists crossed the H5n1 with H3n2 "Swine Fever". To think that would stay contained is utter nonsense. All new virus' have no precedent for immunity. This is how the other flu epidemics started as well, like the Spanish Flu.