There are a few types of influenza and thousands of virus strains, which is why scientists develop the new flu shot each year.
The flu has different carriers too. Flu viruses can spread from animals to humans. This process is referred to as zoonotic transmission and has led to global outbreaks and pandemics. In recent years, you’ve likely heard of those worldwide flu epidemics courtesy of animals. Pigs, chickens and other birds can carry the virus.
And now, bats join the list as animals that might spread the flu.