Antigenic Shift - the Spread of a New, Mutated Virus

Only the influenza Type-A virus is capable of what is known as antigenic shift. The current flu in circulation is an entirely new, mutated pathogen formed from elements of human, pig, and avian virus strains. Overflowing with mutated viruses, the respiratory epithelial host cells of the pig eventually burst open and circulate the new flu virus into the susceptible human population.