How does the flu shot work? How it protects against the flu and why it changes every year

The flu shot works by introducing your body to antigens, which helps your immune system produce antibodies that allow your body to fight infection.
New Scientist

Some viruses like to cheat – and that may be good for our health

Even viruses have to contend with parasites in the form of sponging relatives – and these cheats may be much more common and important than biologists thought. In flu infections, such viruses may ...