A person's throat is a real reservoir of influenza viruses. The virus has the ability to form copies of itself on the sky man. Why the flu has chosen such a localization, scientists are difficult to answer.
In the process of coughing and sneezing irritated soft palate, the formation of microscopic droplets with virus particles. Experiments have shown that even a sharp reduction in the activity of influenza virus by genetic mutation has little effect on the incidence. It's all in the viral protein, the hemagglutinin, its function is to attach to the molecules of sialic acid.
Sialic acid is in the cells of the upper respiratory tract. And formed by the mechanism of attachment of influenza virus to the soft palate. This place is very convenient for the virus. During breathing, coughing, sneezing, he could easily go into the air and be transmitted to others.