inactivated influenza vaccine (IIV)

The inactivated influenza vaccine (IIV) is a flu shot made from killed influenza viruses. Because the viruses are inactivated, they cannot cause illness. When you receive the vaccine, your immune system learns to recognize and fight the flu, helping protect you if you're exposed later. IIV is commonly given via a shot, usually annually, to reduce the risk of catching the flu and its potential complications. It is safe and effective for most people, especially those at higher risk for severe illness, such as older adults, pregnant women, and those with certain health conditions.