Infographic: 10 effective ways to prevent seasonal flu.

Currently, there are four different strains of influenza virus: influenza A, B, C, and D. Of these, strains A and B are the more dangerous, spreading and causing illness in humans, and are the cause of annual seasonal influenza outbreaks. Seasonal influenza spreads very quickly from person to person, mainly through respiratory secretions, which are droplets released when an infected person coughs, sneezes, or talks.