This supports the classical theory that pigs are susceptible to both human and avian influenza viruses, and that they can then serve as 'mixing vessels' for those viruses in pigs that are infected with two or more viruses.
In the time when global epidemic hits the earth time and again; as a veterinarian I thought of sharing this important information to you all.

Pig acts as a mixing vessel for the avian, human and pig influenza virus due to which there's seen an antigenic drift. This antigenic drift is responsible for giving rise to new influenza virus subtypes rapidly. For this new influenza virus, it requires almost a year for developing a vaccine. In this time, this influenza virus would be so rapidly in transmission that it may grow an epidemic and gradually into pandemic disease. Even if we develop vaccine for the virus it is so rapidly in antigenic drift that new subtypes are generated that the vaccine previously discovered would no more work for new subtypes.

The influenza virus of some strains like H1N1, H2N1 and many other infects human as well along with duck and swine. For the new influenza virus body is deprived of memory cells which since human hasn't been into exposure to the new virus and this causes death of individuals. 

For this, we must adopt a preventive measure which can be achieved by rearing pig and other species of animal far from one another being pig a mixing vessel. We must take care while looking after pigs and coming in contact with pigs. Moreover, any products from pig must be examined and consumed after full examination.

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