What is inflammation? Two immunologists explain how the body responds to everything from stings to vaccination and why it sometimes goes wrong

When your body fights off an infection, you develop a fever. If you have arthritis, your joints will hurt. If a bee stings your hand, your hand will swell up and become stiff. These are all manifestations of inflammation occurring in the body.

We are two immunologists who study how the immune system reacts during infections, vaccination and autoimmune diseases where the body starts attacking itself.

While inflammation is commonly associated with the pain of an injury or the many diseases it can cause, it is an important part of the normal immune response. The problems arise when this normally helpful function overreacts or overstays its welcome.