1. Rolfes MA, Foppa IM, Garg S, et al. Estimated influenza illnesses, medical visits, hospitalizations, and deaths averted by vaccination in the united states. https://www.cdc.gov/flu/about/disease/2015-16.htm (accessed 01/31/2019).
2. Estimated influenza illnesses, medical visits, and hospitalizations averted by vaccination in the united states. https://www.cdc.gov/flu/about/disease/2016-17.htm (accessed 01/31/2019).
3. The pathology of influenza virus infections;Taubenberger;Annu Rev Pathol,2008
4. The epidemiology and evolution of influenza viruses in pigs;Brown;Vet Microbiol,2000
5. Pandemic influenza is a zoonosis, as it requires introduction of avian-like gene segments in the human population;Claas;Vet Microbiol,2000