The origins of that flu and 99.9% of others is from villages in China to be exact. 6-8 months before a flu vaccine comes out for the year, they go to villages and test for the flu strain that is most prevalent. They take those few strains and base the current year of vaccines on it.
Regardless of where you are in the world, close quarters always spread disease. Asia having a high population density spreads disease much faster than the US for example, because of the concentrations of humans. The spread due to close quarters is why there are such strict rules on what and who goes in and out of poultry houses.
Vitamins and a balance diet in general helps with immunity. D is provided through diet of caged birds in the end is metabolically identical to that generated in our skin.
Regardless of where you are in the world, close quarters always spread disease. Asia having a high population density spreads disease much faster than the US for example, because of the concentrations of humans. The spread due to close quarters is why there are such strict rules on what and who goes in and out of poultry houses.
Vitamins and a balance diet in general helps with immunity. D is provided through diet of caged birds in the end is metabolically identical to that generated in our skin.