To have immunity against a virus means that a person's body has developed resistance or protection against a specific virus. This can happen naturally when a person is infected with a virus and their immune system produces antibodies to fight the infection. It can also happen through vaccination, where a person is given a weakened or inactive form of the virus to stimulate the body's immune response and build immunity. Once a person has immunity to a virus, they are less likely to become infected with it again or experience severe symptoms if they do become infected.
