Describe the type of immunity for someone who come down with the flu?

As I'm sure you know, being immune to a disease such as influenza (the flu) involves having antibodies to the microorganism that causes the disease (in this case a virus).

Immunity to a disease can be artifical active, artificial passive, natural passive or natural active.

Artifical active immunity occurs when an antigen is injected into the body and antibodies are produced in response (in other words, immunisation). This doesn't apply to your situation.

Artifical passive immunity results when antibodies are injected into the body, such as would be done by a doctor if you were already infected with a microorganism. As above, this doesn't apply to your situation.

Natural passive immunity results when antibodies are given to a person by natural means, such as a baby receiving antibodies from its mother via breast milk. This also doesn't apply to your situation.

Finally, natural active immunity results when you are infected with a microorganism and the body produces antibodies in response. This is what would happen if you were infected with the flu.

So to answer your question, the type of immunity that results when you come down with the flu is natural active immunity.

Active immunity, resulting from the adaptive immune system.

B cells and T cells will have been primed to fight following infections by the same strain of flu, having had the experience with the same type of antigen from this infection. The next time the antigens presented here are presented again (by being infected by the same strain again) the immune system will react more rapidly and strongly. This is the same kind of immunity one could acquire from vaccines.

active immunity